MGI:107931Mice homozygous for one knock-out allele exhibit impaired osteoclastogenesis in response to osteoclastogenic factors. Mice homozygous and heterozygous for a knock-in allele exhibit osteolytic lesion with increased bone formation, mineral apposition rate,and osteoclast numbers. Heterozygosity for the hyperactivating p.S351E mutation leads to hyperkeratosis in stomach and esophagus and, consequently, malnutrition, dehydration and severe growth retardation.