ABCB1 and cancer: Metastasis is recognized as the most critical concern, which accounts for more than 90% of mortality.[5,6] Multidrug resistance (MDR) is now considered as one of the important factors leading to the failure of chemotherapies and cancer treatment in oncology.[7,8] It consists of several processes, such as, increased drug efflux and decreased accumulation of drugs in cells.[8] As a transporter, MDR-associated protein plays a significant role in MDR by affecting drug transportation of cancer cells and the sensitivity of drugs is related to the MDR1 (a member of MDR family) gene polymorphism.[9]