IgF-II/IGF2 [8H1]

The IGFs are mitogenic, polypeptide growth factors that stimulate the proliferation and survival of various cell types, including muscle, bone, and cartilage tissue in vitro. IGFs are predominantly produced by the liver, although a variety of tissues produce the IGFs at distinctive times. The IGFs belong to the Insulin gene family, which also contains insulin and relaxin. The IGFs are similar to insulin by structure and function, but have a much higher growth-promoting activity than insulin. IGF2 expression is influenced by placenta lactogen, while IGF1 expression is regulated by growth hormone. Both IGF-I and IGF2 signal through the tyrosine kinase type I receptor (IGF1R), but IGF2 can also signal through the IGF2/Mannose-6-phosphate receptor. Mature IGFs are generated by proteolytic processing of inactive precursor proteins, which contain N-terminal and C-terminal propeptide regions.