Fig. 6.

Inhibition of P-gp- and ABCG2-mediated transport by P-gp substrates. P-gp-overexpressing MDR-19 cells (A) or ABCG2-overexpressing R-5 cells (B) were incubated with 0.5 μg/ml rhodamine 123 or 5 μM pheophorbide A, respectively, in the absence or presence a specific inhibitor (3 μM Valspodar for P-gp and 10 μM fumitremorgin C for ABCG2) or 25 μM gedatolisib, KW-2478, ispinesib, GSK-690693, AT9283, or AT7519 for 30 minutes after which the medium was removed and replaced with substrate-free medium continuing without or with the inhibitor. Cells incubated with substrates alone are shown by the red histogram, cells incubated with the substrate and specific inhibitor are shown by the teal histogram, and cells incubated with 25 μM concentrations of the test compounds are noted in the key. Results from one of two experiments are shown.