http://www.creativebiomart.net/description_382952_12.htm

Insulin-like growth factor-binding proteins (IGFBPs) control bioavailability, activity, and distribution of insulin-like growth factor (IGF) through high-affinity IGFBP/IGF complexes. Six high-affinity IGF-binding proteins (IGFBP-1 to -6) have been identified, and IGFBP4, the smallest IGFBP expressed by a wide range of cell types, exists in both non-glycosylated and N-glycosylated forms in all biological fluids. Structurally consisting of an IGFBP domain and a thyroglobulin type-I domain, IGFBP4 binds IGF-I and IGF-II with similar affinities as a transport protein and modulates their biological effects. Increasing evidences indicate that IGFBP4 inhibits IGF-induced cellular growth both in vitro and in vivo. As an important member of the IGF system, IGFBP4 is involved in a wide range of biological processes including reproductive physiology, bone formation, renal pathophysiology and carcinomas.