ABCG2 and cancer: In contrast, TP-3654 inhibited ABCG2-mediated efflux of PhA in ABCG2-transfected R482-HEK293 cells (open circles), ABCG2-overexpressing S1-M1-80 (filled circles), and H460-MX20 cancer cells (open squares) in a concentration-dependent manner (Figure 2B), with approximately 60% of the maximum inhibition by 3 μM of Ko143 and the IC50 values of approximately 140, 240, and 200 nM, respectively.