In contrast, we discovered that TP-3654 significantly resensitized ABCG2-overexpressing S1-M1-80 (Figure 1A–C), H460-MX20 (Figure 1D–F) cancer cells and ABCG2-transfected R482-HEK293 cells (Figure 1G–I) to ABCG2 substrate drugs mitoxantrone, SN-38 and topotecan [43,44], in a concentration-dependent manner. The gene discussed is ABCG2; the disease is cancer.