(A) Alkaline comet assay representing the mean tail moments of 50 samples grown in suspension and treated with DMSO, TMZ (100 μM), ABT-888 (100 μM), or TMZ (100 μM) and ABT-888 (100 μM). Samples were stained with SYBR green and analyzed by epiflourescence microscopy; representative images are displayed. (B) Lysates taken from MSH6-wt and MSH6-kd cells were treated with DMSO, TMZ (100 μM), ABT-888 (100 μM), or TMZ (100 μM) and ABT-888 (100 μM) and a control sample collected immediately previous to treatment (Control = C), or 1h, 6h, 1d, and 3d after drug exposure. Western blotting was performed for total and phos-CHK1, total and phos-H2A.X, and actin (controls). (C) MSH6-wt and MSH6-kd cells were grown in suspension and exposed to DMSO, TMZ (100 μM), ABT-888 (100 μM), or TMZ (100 μM) and ABT-888 (100 μM). At days 4 and 7 after treatment cells were stained with EdU and analyzed on the BD LSRII flow cytometer.