Notably, ABC transporters such as multidrug resistance protein1 (MDR1/ABCB1), multidrug resistance-associated protein (MRP1/ABCC1), and breast cancer resistance protein (BCRP/ABCG2) are overexpressed in cancer cells[196], and they can efflux anticancer agents, thereby leading to drug resistance[6]. The gene discussed is ABCG2; the disease is cancer.