A and B, γ-H2AX foci in XPD and XPD-c cells treated with 10 nM Et743 or PM00104 for 6 hours. A, Representative pictures. B, Fold increase of the intensity of γ-H2AX staining normalized to non-treated cells (AU, arbitrary units). Values are averages of five independent experiments. Bars are SEM. C and D, Inhibition of PM00104-induced γ-H2AX by the DNA polymerase inhibitor, aphidicolin (APD). XPD-c cells were pre-incubated with 1μM APD for 15 minutes. PM00104 (10 nM) was then added for 6 additional hours. C, Representative pictures. D, Fold increase of the intensity of γ-H2AX staining normalized to untreated cells (AU, arbitrary units). Values are the average of three independent experiments. Bars are SEM.