ABCB1 and cancer: Encoded by the MDR 1 (MDR1) gene and located on 7q21.1, Pgp is a cell membrane-bound adenosine triphosphate-binding cassette transporter that actively extrudes a variety of chemotherapeutic drugs from cancer cells [1], thereby possibly being responsible for intrinsic and acquired drug resistance in numerous human cancers.By pumping lipophilic drugs out of cells, Pgp reduces intracellular drug concentrations and leads to drug resistance [14].