Elevated colocalization between 53BP1 and Brca1 foci in Pml^C62A/C65Acells. (A) Ratio of 53BP1 foci in MEFs over a 24-hour time course following IR exposure (n = 3 per time point). Two-tailed unpaired Student t test analysis was performed. *P < .05. (B) Representative images of irradiated MEFs immunostained for 53BP1 (red), γH2AX (green), and DAPI (blue). Scale bar, 10 μm. (C) Quantification of 53BP1 and Brca1 foci colocalization 1 hour post-IR in MEFs from 3 independent experiments. Only cells coexpressing 53BP1 and Brca1 foci were counted. Significance was assessed by 2-tailed Mann-Whitney U test. (D) Representative images of irradiated MEFs immunostained for 53BP1 (green), Brca1 (red), and DAPI (blue). Scale bar, 10 μm.