Although the combination treatment of ABCB1 inhibitors with other chemotherapeutic agents displays wishful killing efficacy to a series of drug-resistant cancer cells with overexpression of ABCB1/ABCG2 in tumor models, the clinical trials results of ABCB1 inhibitors still are discouraging due to its nonspecific cytotoxicity to normal tissues [14, 15]. Here, ABCB1 is linked to cancer.