Human IGFBP-6

Human Insulin-like growth factor binding protein-6 (IGFBP-6) is a 213 amino acid glycosylated protein which is a member of a family of six circulating proteins which bind IGF-I and IGF-II with high affinity and modulate their metabolic and mitogenic effects. IGFBP-6 is unique among IGFBPs for its IGF-II binding specificity since it binds IGF-II with a 20-70 fold higher affinity than IGF-I. IGFBP-6 inhibits growth of a number of IGF-II-dependent cancers, including rhabdomyosarcoma, neuroblastoma and colon cancer. Although the major action of IGFBP-6 appears to be inhibition of IGF-II actions, a number of studies suggest that it may also have IGF-independent actions.