IGF-BP3 is a 30 kDa, cysteine-rich secreted protein. It is the major IGF binding protein present in the plasma of human and animals, and it is also found in α-granules of platelets. In addition to its ability to modulate the activity of IGF-I and IGF-II, IGF-BP3 exerts inhibitory effects on follicle stimulating hormone (FSH) activity. Decreased plasma levels of IGF-BP3 often results in dwarfism, whereas elevated levels of IGF-BP3 may lead to acromegaly. The expression of IGF-BP3 in fibroblasts is stimulated by mitogenic growth factors, such as Bombesin, Vasopressin, PDGF, and EGF. Recombinant Human IGF-BP3 is a 28.8 kDa protein consisting of 264 amino acid residues.