NIBRIN (NBN) is a member of the double-strand break repair complex MRE11/RAD50/NBN (MRN) which is involved in DNA double-strand break repair, DNA damage-induced checkpoint activation and plays a critical role in the maintenance of chromosome integrity. NIBRIN contains two modules found in cell cycle checkpoint proteins, a forkhead-associated domain adjacent to a breast cancer carboxy-terminal domain. Mutations in this gene are associated with Nijmegen breakage syndrome and maybe the cause of cancer predisposition and aplastic anemia.Synonyms: Cell cycle regulatory protein p95, NBN, NBS, NBS1, Nijmegen breakage syndrome protein 1, P95