Soon after cancer chemotherapy, a series of drug transporter or DNA repair molecules, such as ATP-binding cassette transporters (ABC transporters), p-glycoprotein (ABCB1, MDR1), MDR-related proteins (MRPs) and so on, work together to dramatically offset therapeutic efficacies and decide the nature of drug resistances and therapeutic failure in individual cancer patients. The gene discussed is ABCB1; the disease is cancer.