RAD51 and Nijmegen breakage syndrome: To specifically investigate the impact of NBS1-P112 on DNA repair we expressed FLAG-NBS1 constructs (WT and P112G) in NBS-ILB1 Nijmegen breakage syndrome patient-derived fibroblasts (Fig. 9C), and examined these lines for HU-induced NBS1 and RAD51 foci formation (Fig. 9D,E).