Insulin is a pancreatic hormone that regulates glucose and is involved in the synthesis of protein and fat. It increases cell permeability to monosaccharides, amino acids and fatty acids. It accelerates glycolysis, the pentose phosphate cycle, and glycogen synthesis in liver. Heterodimer of a B chain and an A chain linked by two disulfide bonds.Belongs to the insulin family. The insulin-link growth factors, IGF-I and IGF-II (also desinated somatomedin C and multiplication stimulating activator, respectvely), share approximatly 76% sequence identity and are 50% related to pro-insulin.IGF-I and IGF-II are nonglycosylated, single chain proteins of 70 and 76 amino acids in length, respectivelly. IGF-I functions as an autocrine regulator of growth in vaious, whereas the function of IGF-II is less well defined.