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Unlabelled: AIM/ BACKGROUND: Various interactions between Caveolae membrane domains, multidrug resistance transporter P-glycoprotein (P-gp) and cholesterol have been suggested. We tested the assumption that anthracycline-induced P-gp and Caveolin-1 have correlated effects on cholesterol distribution in plasma membrane., Materials and Methods: The present study was performed in four lymphoblastic K562 cell lines expressing none (KS), one (Cav and KR cells) or both P-gp and caveolin-1 proteins (CavKR cells)., Results: The CavKR cell line exhibits a significantly higher free cholesterol content than the other cell lines. Cholesterol distribution at the outer leaflet was distinct from the total cellular cholesterol by its accessibility to cholesterol oxidase (COase). When cells were ATP-deprived, cholesterol accessibility to oxidation was significantly delayed in CavKR cells. Caveolin-1 or P-gp expression did not induce detectable changes in membrane cholesterol accessibility to COase., Conclusion: Combination of functional P-gp, caveolae presence and lasting effect of anthracycline treatment appear determinant in free membrane cholesterol homeostasis and likely modulate cholesterol membrane order.