,5 Three ABC transporters, ABCB1 (P-glycoprotein, P-gp), ABCC1 (multidrug resistance protein 1, MRP1), and ABCG2 (breast cancer resistance protein, BCRP), are key players in multidrug resistance (MDR) phenomena in cancer and microbial infectious diseases.6 This evidence concerns the gene ABCG2 and cancer.