Co-amplification ofc-mycandc-erbB-2Oncogenes in a Poorly Differentiated Human Gastric Cancer

c‐erbB‐2 oncogenc has been reported to be frequently amplified in differentiated, tubular type of gastric cancer. Here we report a human gastric cancer which bore co‐amplified c‐myc and c‐erbB‐2 oncogenes: a portion of the amplified c‐erbB‐2 oncogene was found to be rearranged. Furthermore, c‐myc and c‐erbB‐2 oncogenes were over‐expressed in the tumor cells. In contrast to the previous reports, this gastric adenocarcinoma was classified as a poorly differentiated type, and was highly tutnorigenic in nude mice. These results might suggest that activated c‐myc and c‐erbB‐2 oncogenes co‐operate and influence the malignant state of some gastric carcinomas.