ABCB1 and cancer: Among them, the human multidrug resistance protein 1 (MDR1/P-glycoprotein/P-gp), encoded by the ABCB1 gene, and multidrug resistance-associated protein 1 (MRP1), encoded by the ABCC1 gene, increase the efflux of chemotherapeutic drugs, such as doxorubicin (DOX), leading to drug resistance in cancer patients [6,7,8,9].