Figure 3 Reduced DNA repair intermediates in MSH2‐deficient cells. (A) Percentage of untreated (grey) and irradiated (10 Gy) (black) MSH2‐deficient and age‐matched control fibroblasts exhibiting >5 RAD51 foci; 100 γH2AX positive nuclei per experiment were evaluated for the presence of RAD51 foci. (B) Representative immunohistochemical staining of MSH2‐deficient and control cells. The presence of γH2AX foci (red) was used as a marker of double‐stranded DNA damage. Immunostaining of RAD51 (ab213, Abcam) is shown in green and nuclei labelled with Hoechst stain are blue. Bar: 10 μm. (C) Immunoblot of RAD51 protein expression in MSH2‐deficient and age‐matched control fibroblasts. β‐actin loading control is shown.