Abstract
Background: The multidrug resistance (MDR) phenotype reduces the efficacy of various chemotherapies. MDR is linked to the overexpression of ATP-binding cassette (ABC) transporters in cancer cells, including P-glycoprotein (PGP/ABCB1), multidrug resistance protein (MRP1/ABCC1) and breast cancer resistance protein (BCRP/ABCG2). We assessed protein expression patterns of the drug efflux pumps across all tumor types for insight on how to exploit MDR status to circumvent treatment dilemmas.