Description
Insulin-like growth factor 1 (IGF-I) is a member of the IGF family of mitogenic peptide growth factors, along with insulin and IGF-II. IGF-I stimulates proliferation and survival of various cell types including muscle, bone, and cartilage tissue. IGF-1 is produced primarily by the liver as an endocrine hormone as well as in target tissues in a paracrine/ autocrine fashion. The production of IGF-1 is stimulated by growth hormone (GH). Both IGF-I and IGF-II signal through the tyrosine kinase type I receptor (IGF-IR). Proteolytic processing of inactive precursor proteins, which contain N-terminal and C-terminal propeptide regions, generates mature IGFs