Rat IGF1 Recombinant Protein. IGF1 (Insulin-like growth factor-1) is structurally and functionally related to insulin but has a much higher growth-promoting activity. A variety of cellular responses are induced by IGF1, including cell proliferation, differentiation, migration, and survival. Further, IGF1 is a polypeptide growth factor that stimulates the proliferation of a wide range of cell types in muscle, bone, and cartilage tissue. IGF1 stimulates glucose transport in rat bone-derived osteoblastic (PyMS) cells and is effective at much lower concentrations than insulin, not only regarding glycogen and DNA synthesis but also with regards to enhancing glucose uptake. In circulation, IGFs are predominantly bound to binding proteins (IGFBPs)