ABCB1 and acute lymphoblastic leukemia: The mechanisms of tumor failure in the overexpression of drug transporters involved in the expulsion of drugs, such as daunorubicin, doxorubicin, etoposide, vincristine or vinblastine, and mitoxantrone, prevent the drug’s mechanism of action and limit its activity [7–12] Among the most studied transporters is the ABCB1 gene, which encodes a 170-kDa protein called P-glycoprotein (Pgp-170) [13–15] Our group previously reported that 52% of patients with ALL overexpressed the ABCB1 gene, which was associated with lower survival [16].