Analysis of DSB repair. (A) Repair kinetics of Glioblastoma M059K (WT) and M059J (DNA-PKcs deficient) cells after treatment with 50 Gy IR. Repair was performed in media at 37°C. (B) Repair kinetics of LN428 cells after exposure to 100 Gy IR with and without Ligase IV inhibition. LN428 cells were pre-incubated for 24 hours in media with 200 μM Scr7, a Ligase IV inhibitor. Following exposure to IR, cells were allowed to repair in media at 37°C with and without Scr7. Data and error bars represent averages and SEM of three independent experiments, respectively. At least 100 comets were scored for each condition in each experiment. *p < 0.05, Student’s t-test (one-tailed, paired), comparing to WT at each time point.