The Insulin Like Growth Factors, or somatomedins, belong to the Insulin gene family, members of which are insulin and relaxin. The IGFs play similar a similar role to insulin with regards to the regulation of glucose uptake and glycogen metabolism. Additionally IGF1 plays an essential role in mediating many of the effects of growth hormone. IGFs are produced first as inactive precursors, and undergo proteolysis to become active. Circulating IGF1 is produced by hepatocytes whereas local IGF1 is produced in a variety of other tissues where it exhibits paracrine effects. Mouse IGF1 shares 94% and 98% amino acid sequence identity with human and rat IGF1 respectively. Recombinant Mouse IGF1 is a globular, 7.9 kDa protein which contains 3 native disulfide bonds.