ATR is required to maintain genome integrity in 53BP1-deficient cells.

<p>H157 cells were transfected with non-targeting (siNT) or 53BP1 siRNA and then treated with 2.5μM ATRi for 24 hours. Cells were then fixed and stained with DAPI to visualize nuclei (A) and γH2AX to identify sites of DNA damage (B). (C) Quantification of the γH2AX intensity of cells shown in B. Box and whiskers plot shows the mean and the range of the samples, * p<0.01, ns (not significant).