IGFBP-3 and apoptosis - a licence to kill ?

Insulin-like growth factor binding protein (IGFBP)-3, the major carrier of insulin-like growth factors (IGFs) in the circulation, was first isolated a nd characterised over a decade ago. More recently, IGFBP-3 has been assigne d a role as a putative death-promoting factor, a function that appears, und er certain circumstances, to be independent of its IGF-binding ability. Thi s review examines the current evidence for a pro-apoptotic function for IGF BP-3 and speculates on its physiological significance.