PGP and cancer: The ABC transporter family plays significant roles in MDR through decreasing intercellular drug concentrations as drug efflux pump, including P-glycoprotein (P-gp/ABCB1) (first identified ABC transporter), multidrug-resistant protein1 (MRP1/ABCC1), breast cancer–resistant protein (BCRP/ABCG2/MXR/ABCP), and multidrug-resistant protein 10 (ABCC10/MRP7) transporters (Li et al., 2017b).