ABCG2 and cancer: Besides, since the amounts of ABC transporters on cell membrane matter a lot to the overall drug‐transporting activity, the expressions of ABCB1, ABCG2, and ABCC1 in the surface of MDR cancer cells were detected by flow cytometry, with the results of no significant alteration caused by KSQ‐4279 incubation (Figure 5D,E).