ATM and osteosclerosis: C-Abl gene and Atm (ATM Serine/Threonine Kinase) gene result in osteoporosis by positively regulating osteoblast differentiation and bone formation, moreover mice lacking either of them shows osteoporosis, while P53 gene inhibits osteoporosis, which negatively regulates osteoblast differentiation and bone formation, and the knockout mouse shows osteosclerosis (Wang & Li, 2007).