Insulin-like growth factor-binding protein 1 (IGFBP1) is also known as placental protein 12 (PP12), which contains oneIGFBP N-terminal domain and one thyroglobulin type-1 domain. IGFBP1 can bindd both insulin-like growth factors (IGFs) I and II and circulates in the plasma. Binding of IGFBP1 can prolongd the half-life of the IGFs and alterd their interaction with cell surface receptors. Furthermore, IGFBP1 can promote cell migration. Alternate transcriptional splice variants, encoding different isoforms, have been characterized.