ABCG2 and cancer: Drug transport mechanism has been well‐studied in cancer MDR, which is closely associated with up‐regulated drug transport proteins presenting on the surface of cytoplasmic membrane, that is, ATP‐binding cassette (ABC) transporters.30 Drug metabolism is a complicated process of xenobiotics detoxification with the participation of drug metabolism enzymes (DMEs) and the consequent metabolites are transported by ABC transporters.31 As we can see, the concerted efforts of DMEs and ABC transporters finally lead to the decreased drug accumulation in the cytoplasm to reduce drug toxicity.