IGF-I, IGF-II, insulin-like growth factors -1 and -2 are important regulators of signaling that mediates growth and metabolism in cells. Insulin-like growth factor -1 shares structural homology with proinsulin and is mainly produced by liver. IGF-1 acts via specific receptor, IGF-1R, a heterodimeric tyrosine kinase receptor that signals to various second messenger pathways such as MAPK, Raf/Ras and PI3K cascades.
