Membrane transport proteins represented by the ATP-binding cassette (ABC) transport superfamily, including P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), lung resistance protein (LRP), and breast cancer resistance protein (BCRP/ABCG), pump out a variety of chemotherapeutic drugs to increase drug efflux and reduce intracellular concentrations, thereby inducing drug resistance in tumor cells [13]. Here, ABCG2 is linked to neoplasm.