XRCC6 and breast cancer: We generated stable sublines from the breast cancer cell line ZR75.1, which overexpressed either the wild-type S27-S33-Ku70 protein (wt-Ku70), its mutated A27-A33-Ku70 form or the phosphomimetic E27-E33-Ku70 form, using the replicative pEBVsiKu70-CAGKu70(R/S27-S33), pEBVsiKu70-CAGKu70(R/A27-A33), or pEBVsiKu70-CAGKu70(R/E27-E33) plasmids, respectively.