The Insulin-like growth factor binding protein also known as IGFBP serves as a carrier protein for Insulin-like growth factor 1 (IGF-1). Insulin-like growth factor binding protein (IGFBP6) is unique among IGFBPs for its IGF-II binding specificity. IGFBP6 inhibits growth of a number of IGF-II-dependent cancers, including rhabdomyosarcoma, neuroblastoma and colon cancer. Both the N-terminal and C-terminal domains of IGFBP6 contribute to high affinity IGF binding, and the C-terminal domain appears to confer its IGF-II specificity. The three-dimensional structure of the C-domain of IGFBP6 contains a thyroglobulin type 1 fold, and the IGF-II binding site is located in the proximal half of this domain adjacent to the glycosaminoglycan binding site. IGFBP6 is a protein that is encoded by the IGFBP6 gene.