ABCB1 and cancer: P‐gp is an ATP‐binding cassette (ABC) transporter that contributes to MDR in cancer cells, by which P‐gp utilizes the energy from ATP hydrolysis to open the drug pathway through pumping substrates across the membrane.35 However, the understanding about how the expression of ABCB1 was regulated in correlation with the acquisition of chemoresistance in cancer remains controversial.