IGF-binding proteins prolong the half-life of the IGFs and have been shown to either inhibit or stimulate the growth promoting effects of the IGFs on cell culture. They alter the interaction of IGFs with their cell surface receptors. Activates the MAPK signaling pathway and induces cell migration (PubMed:24003225). Interacts (via C-terminal domain) with PHB2. O-linked glycans consist of hexose (probably Gal), N-acetylhexosamine (probably GalNAc) and sialic acid residues. O-glycosylated with core 1 or possibly core 8 glycans. O-glycosylated on one site only in the region AA 143-168 in cerebrospinal fluid.