ABSTRACT
Some varieties of human cancers become resistant, or, are intrinsically resistant to treatment with conventional drug therapies. This phenomenon is due largely to over-expression of the ATP binding cassette, [ABC], super-family of membrane transporters. In this regard, 170 kDa plasma membrane ATP-dependent pump, known as P-glycoprotein are the most important. Other members of multi-drug resistance associated proteins, [MRP], are also involved in multi drug resistance. The function of ABC protein in normal cell is translocation of the endogenous substrate. Ability of cancer cells to become simultaneously resistant to different drugs remains a significant impediment to successful chemotherapy. This review focuses on the mechanism of multi-drug resistance and also gives a brief account of this super family