As shown in Figure 2, increasing concentrations (0–1 μM) of TP-3654 had no significant effect on ABCB1-mediated efflux of calcein in ABCB1-transfected MDR19-HEK293 cells (open circles), ABCB1-overexpressing NCI-ADR-RES (filled circles), or KB-V-1 cancer cells (open squares). Here, ABCB1 is linked to cancer.