In addition, we have demonstrated that REGγ physically binds Chk2 in human cells (12), whereas other studies have shown that REGγ is phosphorylated in an ATM-dependent manner following genotoxic stress (13).DBC1 (Deleted in Breast Cancer 1; KIAA1967; CCAR2) is a nuclear protein encoded by a gene originally described as homozigously deleted in some breast cancers (14–16). This evidence concerns the gene CCAR2 and breast cancer.