Figure 5.

ATR is the key activator of the persistent intra-S-phase checkpoint in DNA-PKcs mutants. (A) Percentage of DNA synthesis over that of unirradiated controls measured after exposure to 10 Gy of IR in the presence or absence of ATRi in M059K cells. (B) As in (A) for M059J cells. (C) As in (A) for V3 cells. Error bars represent the standard deviation from 3 independent experiments. The significance of differences between individual measurements is indicated by * symbol: * p < 0.05, ** p < 0.01, *** p < 0.001.