 IGF-I and IGF-II mRNA levels are significantly increased distal to the site of crush injury in rat sciatic nerves.At the site of nerve repair, locally delivered IGF-I can significantly increase the rate of axon regeneration within a nerve graft and help expedite functional recovery of a paralyzed muscle.Neurite promoting factors include many extracellular matrix proteins produced by Schwann cells at the distal stump including fibronectin and laminin.