Cells were transfected with the siRNAs shown and cultured for 3 days prior to IR treatment (10 Gy) and 6 hr recovery. For small molecule treatments, cells were transfected with siCTRL for consistency, pre-treated with PlaB, DRB, or vehicle (DMSO) (2hrs), IR treatment (10 Gy) and 6 hr recovery in the presence of the small molecules or vehicle. Notably, the total treatment timing for these experiments is the same as experiments in Figure2 Shown are representative images of BRCA1, 53BP1, and γH2AX staining, for such treatments (scale bar = 10 μm). Shown is the percentage cells showing ≥10 foci for each marker shown distinct from siCTRL: *P ≤ 0.0042, †P = 0.034. N = 3, 50 cells analyzed per experiment.