ABCB1 and cancer: Three ABC transporter proteins, P-glycoprotein (P-gp, MDR1, ABCB1), multidrug resistance protein 1 (MRP1, ABCC1), and breast cancer resistance protein (BCRP, ABCG2), have been shown to play a role in multidrug resistance of various types of cancers like OC, breast, lung, colon and others (142).