Insulin-Like Growth Factor II (IGF2) belongs to the insulin family of polypeptide growth factors that is involved in development and growth. Members of this family are structurally homologous to proinsulin, and share higher sequence identity. IGF2 is expressed only from the paternally inherited allele and believed to be secreted by the liver and to circulate in the blood. IGF2 possess growth-promoting activity and can stimulate the proliferation and survival of various cell types including muscle, bone, and cartilage tissue in vitro. IGF2 is influenced by placental lactogen and may play a role in fetal development.