Human IGF-BP3，also known as growth-hormone-dependant binding protein，is a 28.9 kDa cysteine-rich secreted protein. It is the major IGF binding protein present in the plasma of human and animals. In addition to its ability to modulate the activity of IGF-I and IGF-2，IGF-BP3 also 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.
