ABCB1 and acute myeloid leukemia: The over-expression of P-gp, encoded by the ATP Binding Cassette B1 (ABCB1, also known as mdr1) gene, is considered as one of the major obstacles to successful cancer chemotherapy.[1] P-gp is a trans-membrane glycoprotein which reduces intracellular drug concentrations by pumping drugs out of the cells.[2] Numerous studies have confirmed that the expression of P-gp is an adverse prognostic factor for complete remission and survival in adult AML.[3], [4] Unfortunately, the efflux-pump modulators used in clinic have been proved disappointing.