[Biology and clinical relevance of multidrug resistance associated antigen]

Multidrug resistance (MDR) is a main obstacle to cancer chemotherapy. P-glycoprotein(P-gp) is the first antigen discovered to be linked to MDR, and is a energy dependent plasma membrane efflux pump, which actively transports a variety of drugs and substances out of cells. P-gp can be detected by immunological or biochemical (molecular) methods, but both methods have some limitations with respect to sensitivity and specificity. Some studies have demonstrated the adverse prognostic factor of P-gp and some others have not. The discrepancy between various studies is considered to be due to the limitation of methodology for detecting P-gp and the existence of other MDR antigens, for example multidrug resistance associated protein. The clinical roles of MDR reversing agents have not yet been confirmed.