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Recent studies have shown that transmembrane‐type tight junction proteins are upregulated in various cancers compared with their levels in normal tissues and are involved in cancer progression, suggesting that they are potential therapeutic targets. Here, we demonstrated the expression profile and a novel role of junctional adhesion molecule‐A (JAM‐A) in breast cancer. Immunohistochemistry of surgical specimens showed that JAM‐A was highly expressed from carcinoma in situ lesions, as in other adenocarcinomas, with higher expression in invasive carcinomas. High expression of JAM‐A contributed to malignant aspects such as lymph node metastasis and lymphatic involvement positivity. In breast cancer cells, JAM‐A expression status affects malignant potentials including proliferation and migration. Multilayered proteomics revealed that JAM‐A interacts with the amino acid transporter LAT1 in breast cancer cells. JAM‐A regulates the expression of LAT1 and interacts with it on the whole cell membrane, leading to enhanced amino acid uptake to promote tumor growth. Double high expression of JAM‐A and LAT1 predicts poor prognosis in patients with breast cancer. Of note, an antibody against an extracellular domain of JAM‐A suppressed the proliferation of breast cancer cells. Our findings indicate the possibility of JAM‐A‐targeted therapy ideally combined with LAT1‐targeted therapy as a new therapeutic strategy against breast cancer. [ABSTRACT FROM AUTHOR]

Eribulin inhibits microtubule polymerization and improves the overall survival of patients with recurrent metastatic breast cancer. A subgroup analysis revealed a low neutrophil to lymphocyte ratio (NLR) (<3) to be a prognostic factor of eribulin treatment. We thus hypothesized that eribulin might be related to the immune response for breast cancer cells and we analyzed the effects of eribulin on the immune system. Immunohistochemical staining revealed that human leukocyte antigen (HLA) class I expression was increased in clinical samples after eribulin treatment. In vitro assays revealed that eribulin treatment increased HLA class I expression in breast cancer line cells. RNA‐sequencing demonstrated that eribulin treatment increased the expression of the NOD‐like family CARD domain‐containing 5 (NLRC5), a master regulator of HLA class I expression. Eribulin treatment increased the NY‐ESO‐1‐specific T‐cell receptor (TCR) transduced T (TCR‐T) cell response for New York oesophageal squamous cell carcinoma 1 (NY‐ESO‐1) overexpressed breast cancer cells. The eribulin and TCR‐T combined therapy model revealed that eribulin and immunotherapy using TCR‐T cells has a synergistic effect. In summary, eribulin increases the expression of HLA class 1 via HLA class 1 transactivatior NLRC5 and eribulin combination with immunotherapy can be effective for the treatment of breast cancer. [ABSTRACT FROM AUTHOR]

In this review, we discuss the possibility of the vitamin D metabolizing enzyme CYP24A1 being a therapeutic target for various tumors including breast, colorectal and prostate tumors. Given the pleiotropic cellular activity of vitamin D, its deficiency impairs its physiological function in target cells and results in various pathologies including cancer. In addition, accumulated data have shown that elevated expression of CYP24A1 promotes carcinogenesis in various cancer subtypes by decreasing the bioavailability of vitamin D metabolites. Thus, we propose the potential feasibility of vitamin D metabolism-blocking therapy in various types of human malignancies that express constitutive CYP24A1. [ABSTRACT FROM AUTHOR]

Since its discovery in late 2019, severe acute respiratory syndrome coronavirus 2 has spread around the world, causing millions of deaths due to coronavirus disease 2019 (COVID-19). Numerous clinical and post-mortem investigations of COVID-19 cases have found myriad clinical and pathological manifestations of the disease. In this report, we present three autopsy cases in which, despite weaning from extracorporeal membrane oxygenation (ECMO), extensive intestinal epithelial shedding, probably due to ischemia, was followed by massive watery diarrhea and the spread of infection via the portal vein due to bacterial translocation, which resulted in cholangitis lenta. Thrombophilia was attributed to ECMO usage and COVID-19-related vascular endothelial damage. These cases provide instructive findings showing that the loss of the intestinal barrier may be the underlying cause of severe watery diarrhea and liver failure in COVID-19 patients, especially with ECMO usage. [ABSTRACT FROM AUTHOR]

Retinoic acid (RA) is an active metabolite of vitamin A, which is an essential signaling molecule involved in cell fate decisions, such as differentiation, proliferation, and apoptosis, in a wide variety of cell types. Accumulated data have demonstrated that expression of RA-metabolizing enzymes, CYP26A1, B1, and C1 (cytochrome P450, family 26A1, B1, and C1, respectively), protects cells and tissues from exposure to RA through restriction of RA access to transcriptional machinery by converting RA to rapidly excreted derivatives. CYP26 enzymes play similar but separate roles in limiting the consequences of fluctuations in nutritional vitamin A. Recently, we found that RA depletion caused by expression of CYP26A1 promotes malignant behaviors of tumor cells derived from various tissues, implicating CYP26A1 as a candidate oncogene. We also showed that the expression levels of CYP26 enzymes are elevated in various types of cancer. We have provided evidence for oncogenic and cell survival properties of CYP26 enzymes, indicating that these molecules are possible therapeutic targets for CYP26-expressing malignancies. [ABSTRACT FROM AUTHOR]

Recent studies have revealed that aberrant expression of tight junction (TJ) proteins is a hallmark of various solid tumors and it is recognized as a useful therapeutic target. Claudin‐6 (CLDN6), a member of the family of TJ transmembrane proteins, is an ideal therapeutic target because it is not expressed in human adult normal tissues. In this study, we found that CLDN6 is highly expressed in uterine cervical adenocarcinoma (ADC) and that high CLDN6 expression was correlated with lymph node metastasis and lymphovascular infiltration and was an independent prognostic factor. Shotgun proteome analysis revealed that cell‐cell adhesion‐related proteins and drug metabolism‐associated proteins (aldo‐keto reductase [AKR] family proteins) were significantly increased in CLDN6‐overexpressing cells. Furthermore, overexpression of CLDN6 enhanced cell‐cell adhesion properties and attenuated sensitivity to anticancer drugs including doxorubicin, daunorubicin, and cisplatin. Taken together, the results indicate that aberrant expression of CLDN6 enhances malignant potentials and drug resistance of cervical ADC, possibly due to increased cell‐cell adhesion properties and drug metabolism. Our findings provide an insight into a new therapeutic strategy, a CLDN6‐targeting therapy, against cervical ADC. [ABSTRACT FROM AUTHOR]

Claudins are major components of tight junctions that maintain cell polarity and intercellular adhesion. The dynamics of claudins in cancer cells have attracted attention as a therapeutic target. During carcinogenesis, claudin expression is generally downregulated; however, overexpression of claudin-18.2 has been observed in several types of cancers. Upregulated and mislocalized claudin-18.2 expression in cancer cells has been suggested as a therapeutic target. Research on claudin-18.2 has revealed its involvement in carcinogenesis. Clinical trials using zolbetuximab, a monoclonal antibody targeting claudin-18.2, for patients with advanced cancer yielded positive results with few high-grade adverse events; thus, it is expected to be a novel and effective therapeutic. Here, we review current insights into the role that claudin-18.2 plays in basic cancer research and clinical applications. A better understanding of these roles will facilitate the development of new treatment strategies for cancer patients with poor prognoses. [ABSTRACT FROM AUTHOR]

Indocyanine green (ICG) fluorescence imaging has been used for blood flow assessment in anastomoses in the field of colorectal cancer surgery. However, whether ICG fluorescence is related to the presence of cancer cells in the lymph nodes is unclear. We explored the utilization of ICG fluorescence in colorectal cancer surgery. ICG was injected into the submucosa around the tumor before radical resection in colorectal cancer patients. Intraoperatively, near-infrared (NIR) fluorescence was used for lymphatic flow visualization. After specimen removal, harvested lymph nodes were classified as positive or negative based on the detection of fluorescence, followed by pathological examination. ICG distribution on a section of each lymph node was examined by fluorescence microscopy. Overall, 155 patients underwent real-time NIR fluorescence imaging-guided surgery. Altogether, 1,017 lymph nodes were retrieved from these patients. Metastatic lymph nodes were present in 36 (5.8%) of 622 fluorescence-negative lymph nodes, which was significantly higher than 11 (2.8%) of 395 fluorescence-positive lymph nodes (odds ratio: 2.15, P = 0.03). Fluorescence microscopy of metastatic lymph nodes showed that ICG fluorescence was present in the normal structural region but not in the cancerous region of the lymph nodes. Furthermore, ICG fluorescence was observed in all metastatic lymph nodes, except those with cancer cells occupying >90% of the total area. ICG fluorescence detected only the normal parts of the lymph node draining from the peritumoral area and not the cancer tissues. This finding is important for developing appropriate strategies for navigation surgery using NIR fluorescence. [ABSTRACT FROM AUTHOR]

Amyloidosis is induced by extracellular deposition of certain proteins. Thirty-six proteins have so far been identified as amyloidogenic proteins in humans. Although it is very important to determine the specific amyloid protein type for the choice of therapy for amyloidosis patient, it might be difficult to identify specific proteins from amyloid-deposited tissue. Apolipoprotein A-IV is known as an amyloid-associated protein, but there have been few reports of apolipoprotein A-IV amyloidosis. Here we report a case of systemic apolipoprotein A-IV-associated amyloidosis that was confirmed by proteome analysis using formalin-fixed paraffin-embedded tissue and an immunohistochemical technique. [ABSTRACT FROM AUTHOR]

Recent studies have shown that aberrant expression of tight junction proteins (TJP) contributes to malignant potential of various cancers. In the present study, we investigated the expression of junctional adhesion molecule‐A (JAM‐A), one of the transmembrane TJP, in uterine cervical adenocarcinoma and the significance of its expression for malignancy. Immunohistochemistry on human surgical specimens showed that JAM‐A was aberrantly expressed in neoplastic regions including adenocarcinoma in situ (AIS). Knockout of JAM‐A significantly suppressed cell proliferation and colony‐forming and migration abilities. We also showed that an antibody specific to an extracellular region of JAM‐A reduced cell proliferation ability and that loss of JAM‐A increased drug sensitivity of cervical adenocarcinoma cells. Based on a comprehensive proteome analysis, we found that poliovirus receptor (PVR/CD155) was regulated by JAM‐A and formed a physical interaction with JAM‐A. In human surgical specimens, PVR/CD155 expression was significantly correlated with some clinicopathological features and prognosis of cervical adenocarcinoma. Interestingly, most of the PVR/CD155‐positive cases expressed a high level of JAM‐A, and patients with the expression pattern of PVR/CD155 positive/JAM‐A high had significantly shorter periods of relapse‐free survival (P =.00964) and overall survival (P =.0204) than those for the other patients. Our observations suggest that aberrant expression of JAM‐A promotes malignancy of uterine cervical adenocarcinoma by regulation of PVR/CD155, and JAM‐A is therefore a potential therapeutic target for this malignancy. [ABSTRACT FROM AUTHOR]

Introduction: Delayed gastric emptying (DGE) remains an important problem after pancreaticoduodenectomy (PD). There is a lack of effective treatments for early recovery of oral dietary intake. Rikkunshito (RKT), a Japanese herbal medicine, has been gaining attention as a facilitator of gastric emptying. We evaluated the effects of RKT on DGE after PD. Methods: In this prospective, randomized, open-labeled study, patients were randomly allocated before PD in a 1:1 ratio to the RKT group or the control group that received no additional treatment. The RKT group received 2.5 g of RKT three times daily (7.5 g/day) from postoperative day (POD) 1 to POD 21. The primary endpoint was the incidence of DGE. Secondary endpoints were short-term postoperative outcomes including oral dietary intake volume and perioperative changes in levels of the hormones ghrelin and leptin. Patients were observed until hospital discharge. Results: Twenty-six patients in each group (n = 52) completed the protocol treatment and were included in the analysis set. There were no statistically significant differences in basic characteristics and operative factors. The overall incidence of DGE was not statistically different between the RKT and control groups (30.8% vs 30.8%, p> 0.9999). There were no statistically significant differences in the amount of postoperative oral dietary intake represented by total dietary intake (TDI) up to POD 14 and POD 21, complications, and length of hospital stay. No adverse events related to this study were observed. In the RKT group, total ghrelin and acyl-ghrelin were significantly upregulated and leptin was significantly downregulated earlier than in the control group. Conclusion: RKT treatment from POD 1 to 21 did not reduce the incidence of DGE and had no clinically beneficial effect on short-term postoperative outcomes irrespective of changes in hormone levels. [ABSTRACT FROM AUTHOR]

Claudin7 (cld7) is a cancer‐initiating cell (CIC) marker in gastrointestinal tumors, a cld7‐knockdown (kd) being accompanied by loss of tumor progression. Tumor exosomes (TEX) restoring CIC activities, we explored the contribution of cld7. This became particularly interesting, as tight junction (TJ)‐ and glycolipid‐enriched membrane domain (GEM)‐derived cld7 is recruited into distinct TEX. TEXs were derived from CIC or cld7kd cells of a rat pancreatic and a human colon cancer line. TEX derived from pancreatic cancer cld7kd cells rescued with palmitoylation site‐deficient cld7 (cld7mP) allowed selectively evaluating the contribution of GEM‐derived TEX, only palmitoylated cld7 being integrated into GEM. Cld7 CIC‐TEX promoted tumor cell dissemination and metastatic growth without a major impact on proliferation, apoptosis resistance and epithelial–mesenchymal transition. Instead, migration, invasion and (lymph)angiogenesis were strongly supported, only migration being selectively fostered by GEM‐derived cld7 TEX. CIC‐TEX coculture of cld7kd cells uncovered significant changes in the cld7kd cell protein and miRNA profiles. However, changes did not correspond to the CIC‐TEX profile, CIC‐TEX rather initiating integrin, protease and RTK, particularly lymphangiogenic receptor activation. CIC‐TEX preferentially rescuing cld7kd‐associated defects in signal transduction was backed up by an RTK inhibitor neutralizing the impact of CIC‐TEX on tumor progression. In conclusion, cld7 contributes to selective steps of the metastatic cascade. Defects of cld7kd and cld7mP cells in migration, invasion and (lymph)angiogenesis are effaced by CIC‐TEX that act by signaling cascade activation. Accordingly, RTK inhibitors are an efficient therapeutic defeating CIC‐TEX. What's new? Cancer‐initiating cells (CICs) fuel tumor onset and chemotherapy resistance. CIC activity relies on the transfer of signals to target cells by tumor exosomes (TEXs). It remains unclear, however, whether incoming TEX content reprograms target cells to facilitate tumor progression. Here, Claudin 7, a CIC biomarker, was recovered from TEX populations derived from rat pancreatic cancer cells and human colorectal cancer cells. Claudin 7 CIC‐TEXs demonstrated an ability to reprogram nonmetastasizing tumor cells, resulting in promotion of tumor cell migration, invasion, and lymphangiogenesis. CIC‐TEX activity was associated with integrin and RTK and GPCR signaling. Inhibition of RTK neutralized CIC‐TEX tumor progression. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the rate of positive surgical margins for magnetic resonance imaging (MRI) performed in the supine position prior to breast-conserving surgery (BCS). The rate of positive surgical margins and the clinicopathological factors were examined in consecutive patients with BCS who underwent preoperative MRI performed in the supine position at Sapporo Medical University Hospital (Sapporo, Japan) and related hospitals and clinics between January 2012 and December 2013. Of 1,175 eligible patients, 1,150 were included after excluding 25 patients with either bilateral breast cancer or stage IV disease. Positive margin was defined as no cancer seen on the resected margin. The primary endpoint was the rate of positive surgical margins when preoperative MRI was performed in the supine position and the secondary endpoint was identification of the factors that predict positive margins. Of the 1,150 female patients (median age, 55 years; range, 29-97 years) who underwent BCS for breast cancer following MRI performed in the supine position, 215 (18.8%) had positive margins, which is similar to the rate with MRI in the prone position, and 930 (81.2%) had negative margins. The rate of positive surgical margins in patients of the human epidermal growth factor receptor 2 (HER2) type was significantly higher than that in the non-HER2 type group (6.5 and 2.9%; χ2 P=0.0103). There was no increase in the rate of positive margins in breast cancers with a diameter of >T2. The rate of positive surgical margins following MRI performed in the supine position was 18.8%. Supine MRI appears to be suitable for informing on the extent of resection of breast cancer. [ABSTRACT FROM AUTHOR]

The proper use of anthracycline-containing regimens in combination with anti-HER2-targeted therapy in a neoadjuvant setting for patients with HER2-positive breast cancer has not been resolved. Regimens preceded by anthracyclines have become the standard of care, and although the order has no significant impact on HER2-negative breast cancer, it is inconclusive as to whether a taxane-first sequence would have a similar effect on HER2-positive breast cancer. The present study aimed to investigate the benefit of a taxane-first sequence and of adriamycin and cyclophosphamide (AC) in patients with non-clinical complete response (non-cCR) to pertuzumab, trastuzumab and docetaxel (PTD). The present single-center prospective observational study was performed to investigate PTD followed by AC, and aimed to clarify the cCR rate after PTD alone and the pathological clinical response (pCR) rate after subsequent AC in patients without cCR after PTD alone. A total 24 patients were analyzed; of these, 14 achieved pCR (pCR rate, 58.3%). While four of 14 patients (28.6%) in the intention-to-treat population achieved pCR, nine of 14 patients (64.3%) achieved pCR with AC but not cCR after PTD. The median tumor reduction rate after four cycles of PTD was 58.9% (range, 20.8-100%) in all 24 patients, whereas the reduction rate after PTD-AC was 76.9% (range, 31.1-100%). Cardiac serious adverse events occurred in three patients (12.5%). In conclusion, a high pCR rate was observed for the taxane-first sequence. Patients were highly responsive to PTD, but some cases achieved additional antitumor effects after AC, which resulted in pCR without cCR after PTD alone. Since cardiotoxicity remains a significant problem, a higher risk-benefit treatment strategy is required to aim for AC omission. Trial registration number: UMIN000046338, name of registry: UMIN-CTR, date of registration: December 10, 2021. [ABSTRACT FROM AUTHOR]

The use of endoscopic submucosal dissection ( ESD) for duodenal neoplasms has increased in recent years, but delayed perforation and bleeding are also known to frequently occur. We present two cases in which duodenal adenoma was successfully treated with laparoscopic-endoscopic cooperative surgery. ESD was combined with laparoscopic seromuscular sutures. The lesions in both cases were located in the second portion of the duodenum. The patients requested resection of the lesion, and we performed laparoscopic-endoscopic cooperative surgery. After the laparoscopic surgeon mobilized the duodenum, the endoscopic surgeon performed ESD for the duodenal tumor without perforation. The laparoscopic surgeon sutured the duodenal wall in the seromuscular layer to strengthen the ulcer bed after ESD. Histopathological studies confirmed that the surgical margins were tumor-free in both cases. The patients were discharged with no complications. This unique laparoscopic-endoscopic cooperative procedure is a safe and effective method for resecting superficial nonampullary duodenal tumors. [ABSTRACT FROM AUTHOR]

The tight junction protein claudin-4 is frequently overexpressed in pancreatic cancer, and is also a receptor for Clostridium perfringens enterotoxin (CPE). The cytotoxic effects of CPE are thought to be useful as a novel therapeutic tool for pancreatic cancer. However, the responses to CPE via claudin-4 remain unknown in normal human pancreatic duct epithelial (HPDE) cells. We introduced the human telomerase reverse transcriptase (hTERT) gene into HPDE cells in primary culture as a model of normal HPDE cells in vitro. hTERT-HPDE cells treated with or without 10% FBS and pancreatic cancer cell lines PANC-1, BXPC3, HPAF-II and HPAC were treated with CPE. In Western blotting, the expression of claudin-4 protein in hTERT-HPDE cells treated with 10% FBS was as high as it was in all of the pancreatic cancer cell lines. In hTERT-HPDE cells with or without 10% FBS, cytotoxicity was not observed at any concentration of CPE, whereas in all pancreatic cancer cell lines, CPE had a dose-dependent cytotoxic effect. In hTERT-HPDE cells with 10% FBS, claudin-4 was localized in the apical-most regions, where there are tight junction areas, in which in all pancreatic cancer cell lines claudin-4 was found not only in the apical-most regions but also at basolateral membranes. In hTERT-HPDE cells with 10% FBS after treatment with CPE, downregulation of barrier function and claudin-4 expression at the membranes was observed. In HPAC cells, the sensitivity to CPE was significantly decreased by knockdown of claudin-4 expression using siRNA compared to the control. These findings suggest that, in normal HPDE cells, the lack of toxicity of CPE was probably due to the localization of claudin-4, which is different from that of pancreatic cancer cells. hTERT-HPDE cells in this culture system may be a useful model of normal HPDE cells not only for physiological regulation of claudin-4 expression but also for developing safer and more effective therapeutic methods targeting claudin-4 in pancreatic cancer. [ABSTRACT FROM AUTHOR]

Simple Summary: Most patients with a pancreatic ductal adenocarcinoma develop a recurrence after surgery. Predictive factors may therefore guide therapeutic decision-making. We aimed to identify perioperative predictors of the early recurrence of pancreatic ductal adenocarcinomas. We found that preoperative (>52 U/mL) and postoperative (>37 U/mL) elevated carbohydrate antigen 19-9 levels as well as a tumor size >3.0 cm were independently associated with an early recurrence after a pancreatectomy. Furthermore, an early recurrence resulted in a more frequent liver metastasis than a late recurrence, suggesting that patients experiencing a recurrence within 12 months had undetectable micrometastases. Further studies are needed to identify new biomarkers for the detection of clinically occult micrometastases during surgery as current preoperative risk factors are inadequate to accurately identify patients susceptible to an early recurrence of pancreatic ductal adenocarcinomas. We aimed to identify the perioperative predictors of the early recurrence (ER) of resectable and borderline-resectable pancreatic ductal adenocarcinomas (PDACs). After surgery for a PDAC, most patients develop a recurrence. Predictive factors may therefore guide therapeutic decision-making. Patients (n = 234) who underwent a pancreatectomy for a PDAC between 2006 and 2019 were included. The postrecurrence survival (PRS) was estimated using Kaplan–Meier curves. Predictive factors for an ER were assessed using logistic regression analyses; 93 patients (39.7%) were recurrence-free at the last follow-up. Patients with an ER (n = 85, 36.3%), defined as a recurrence within the first 12 months after surgery, had 1- and 2-year PRS rates of 38.7% and 9.5%, respectively, compared with 66.9% and 37.2% for those with a late recurrence (n = 56, 23.9%; both p < 0.001). The most common site of an ER was the liver (55.3%) with a significantly shorter median overall survival time than that with either a local or a lung recurrence (14.5 months; p < 0.001). Preoperative and postoperative risk factors for an ER included a tumor size >3.0 cm (odds ratio (OR): 3.11, 95% confidence interval (CI): 1.35–7.14) and preoperative carbohydrate antigen 19-9 (CA19-9) levels >52 U/mL (OR: 3.25, 95% CI: 1.67–6.30) and a pathological tumor size >3.0 cm (OR: 2.00, 95% CI: 1.03–3.90) and postoperative carbohydrate antigen 19-9 levels >37 U/mL (OR: 2.11, 95% CI: 1.02–4.36), respectively. Preoperatively (>52 U/mL) and postoperatively (>37 U/mL) elevated CA19-9 and a tumor size >3.0 cm were independent predictors for an ER after a pancreatectomy for a PDAC. [ABSTRACT FROM AUTHOR]

Aberrant expression of tight junction proteins has recently been focused on in the cancer research field. We previously showed that claudin-1 is aberrantly expressed from an early stage of uterine cervical adenocarcinoma and contributes to malignant potentials. To elucidate the molecular mechanisms underlying tumor-promoting roles of claudin-1, we established and analyzed claudin-1 knockout cells. Knockout of claudin-1 suppressed conventional tight junctional functions, barrier and fence functions, and expression of cell adhesion-associated proteins including E-cadherin. Comparative proteome analysis revealed that expression of claudin-1 affected expression of a wide range of proteins, especially proteins that are associated with cell adhesion and actin cytoskeleton remodeling. Interactome analysis of the identified proteins revealed that E-cadherin and focal adhesion kinase play central roles in the claudin-1-dependently affected protein network. Moreover, knockout of claudin-1 significantly suppressed microvilli formation and activity of Ezrin/Radixin/Moesin. Taken together, the results indicate that expression of claudin-1 affects not only conventional tight junction function but also expression and activity of a wide range of proteins, especially proteins that are associated with cell adhesion and actin cytoskeleton remodeling, to contribute to malignant potentials and microvilli formation in cervical adenocarcinoma cells. • Phase transfer surfactants are employed for proteomics of claudin-1 knockout cells. • Cell adhesion- and actin-related proteins are reduced in claudin-1 knockout cells. • E-cadherin and FAK play central roles in the claudin-1-dependent protein network. • Microvilli formation and activity of ERM proteins are regulated by claudin-1. [ABSTRACT FROM AUTHOR]