The insulin-like growth factor (IGF) pathway is involved in the normal control of fetal development, tissue growth, and metabolism. Two distinct ligands (insulin-like growth factor-1 [IGF-1] and IGF-2) plus insulin, and two receptors (insulin-like growth factor receptor-1 [IGF-1R] and the insulin receptor) capable of both homo- and heteropolymerization mediate the actions of this pathway. Cellular functions of IGF-regulated signaling are influenced by the expression of a variety of receptor docking proteins, including four different insulin receptor substrate proteins.
