The insulin-like growth factors possess growth-promoting activity (By similarity). Major fetal growth hormone in mammals. Plays a key role in regulating fetoplacental development. IGF2 is influenced by placental lactogen. Also involved in tissue differentiation. In adults, involved in glucose metabolism in adipose tissue, skeletal muscle and liver. Acts as a ligand for integrin which is required for IGF2 signaling. Positively regulates myogenic transcription factor MYOD1 function by facilitating the recruitment of transcriptional coactivators, thereby controlling muscle terminal differentiation (By similarity). Inhibits myoblast differentiation and metabolism via increasing the mitochondrial respiration rate (By similarity). Preptin undergoes glucose-mediated co-secretion with insulin, and acts as physiological amplifier of glucose-mediated insulin secretion. Exhibits osteogenic properties by increasing osteoblast mitogenic activity through phosphoactivation of MAPK1 and MAPK3. Interacts with MYORG; this interaction is required for IGF2 secretion. Interacts with integrins ITGAV:ITGB3 and ITGA6:ITGB4; integrin-binding is required for IGF2 signaling. Expressed predominantly in fetal tissues and at lower levels in adult. Proteolytically processed by PCSK4, proIGF2 is cleaved at Arg-128 and Arg-92 to generate big-IGF2 and mature IGF2. The IGF2 locus is imprinted. Paternal inherited gene is expressed, while the maternal inherited gene is imprinted, hence silenced. Belongs to the insulin family.