The insulin-like growth factors possess growth-promoting activity (PubMed:29440408). Major fetal growth hormone in mammals. Plays a key role in regulating fetoplacental development (Probable) (PubMed:2330056, PubMed:12087403). IGF2 is influenced by placental lactogen (Probable). Also involved in tissue differentiation (Probable). In adults, involved in glucose metabolism in adipose tissue, skeletal muscle and liver (Probable). Acts as a ligand for integrin which is required for IGF2 signaling (By similarity). Positively regulates myogenic transcription factor MYOD1 function by facilitating the recruitment of transcriptional coactivators, thereby controlling muscle terminal differentiation (PubMed:16901893). Inhibits myoblast differentiation and modulates metabolism via increasing the mitochondrial respiration rate (PubMed:32557799). 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 (PubMed:19706595). Interacts with integrins ITGAV:ITGB3 and ITGA6:ITGB4; integrin-binding is required for IGF2 signaling (By similarity). Expressed in the heart, blood serum, kidney and skeletal muscle including the tibialis anterior muscle. At 8 dpc, 9.5 dpc and 16.5 dpc, transcripts from parental allele are detected in embryonic and extraembryonic tissues (PubMed:28522536, PubMed:1997210). At 16.5 dpc, transcripts from parental and maternal alleles are detected only in the choroid plexus and the leptomeninges (PubMed:1997210). Expressed in fetal muscle and brain tissue at 12.5 dpc (PubMed:29440408). Low levels of expression during myoblast proliferation. Levels rise rapidly during myoblast differentiation and then decrease. Predominant isoform expressed in fetal muscle tissues at 12.5 dpc. Proteolytically processed by PCSK4, proIGF2 is cleaved at Arg-128 and Arg-92 to generate big-IGF2 and mature IGF2. Heterozygous animals are smaller than their wild type littermates but appear normal, reach sexual maturity and are fertile (PubMed:2330056). Transmission of this mutation through the male germline results in heterozygous progeny that are growth deficient. In contrast, when the disrupted gene is transmitted maternally, the heterozygous offspring are phenotypically normal. Homozygous mutants are indistinguishable in appearance from growth-deficient heterozygous siblings (PubMed:1997210). Mutant animals for transcript P0 specifically show a reduced growth of the placenta followed by fetal growth restriction, passive permeability for nutrients of the placenta is decreased (PubMed:12087403). The IGF2 locus is imprinted. Paternal inherited gene is expressed, while the maternal inherited gene is imprinted, hence silenced (PubMed:1997210). It is differentially regulated in the placenta and fetus, transcribed from 3 promoters P1, P2 and P3 in both fetus and placenta and additionally from a fourth placental-specific promoter, P0 (Probable). Product of 4 different transcripts regulated by 4 different promoters, denominated P0, P1, P2 and P3. Belongs to the insulin family.