The insulin-like growth factor binding proteins (IGFBPs).
|IGFBP|| (kDa)||Relative affinity for IGFs||Possible functions|
|1||25||Inhibition of growth-promoting actions of IGFs and inhibition of insulin-like actions, integrin binding, glucose homeostasis|
|2||31||Stimulation of splenic growth, suppression of IGF bioactivity, cell surface binding, mitogenic for some cell types|
|3||29||Inhibition of IGF actions, induction of apoptosis|
|4||26||Inhibition or enhancement of IGF actions, inhibition of ovarian steroidogenesis, regulation of bone formation|
|5||28||Localises IGFs in extracellular matrix and bone, regulation of IGF bioavailability|
|6||23||Inhibition of actions of IGF-II|