DEK counteracts the effect of ABT-888 on RPA foci formation under HU treatment.

U2-OS control and shDEK cells were pulse-labelled with EdU, then either left untreated or treated with 2 mM HU for 80 min in presence or absence of 1 μM ABT-888. RPA foci (green) were visualized via indirect immunofluorescence, EdU (magenta) using click chemistry. DNA was counterstained with Hoechst 33342 (cyan). (A) Representative confocal images for each experimental condition. Scale bar: 5 μm. (B-C) Quantification of three independent experiments. At least 97 cells were scored per experimental condition. Error bars represent the S.E.M. t-test: *p≤0.05, **p≤0.01, ***p≤0.001. ABT-888 treated cells: hatched bars. (B) Percentage of RPA positive S-phase cells as determined using the automated foci counter of the BIC macro tool box (see also S6 Fig). (C) Mean nuclear RPA fluorescence intensities of the same S-phase cells as in (B).