ABCB1 and neoplasm: ABC proteins that confer drug resistance include P-glycoprotein (genes symbol ABCB1), the multidrug resistance protein 1 (MRP1, gene symbol ABCC1), MRP2 (gene symbol ABCC2) and the breast cancer resistance protein (BCRP, gene symbol ABCG2), induce the drug efflux from tumor cells and decrease cellular drug accumulation47.