IGFBP3 also known as Insulin-like growth factor binding protein 3 isoform b precursor. They are structurally and functionally related to insulin but have a much higher growth-promoting activity. It may be a physiological regulator of [1-14C]-2-deoxy-D-glucose (2DG) transport and glycogen synthesis in osteoblasts. It stimulates glucose transport in rat bone-derived osteoblastic (PyMS) cells and is effective at much lower concentrations than insulin, not only regarding glycogen and DNA synthesis but also with regard to enhancing glucose uptake. It may play a role in synapse maturation. Recombinant human IGFBP3, fused to His-tag at N-terminus, was expressed in E.coli.