 NGF has not only a trophic role but also a tropic or guiding role.The Schwann cells that form the bands of Bungner at the distal injury site express NGF receptors as a guiding factor for the regenerating axon of the injured neuron.NGF bound to the receptors on Schwann cells provides the growing neurons that are contacted with a trophic factor to promote further growth and regeneration

Ciliary neurotrophic factor (CNTF) typically has a high level of expression in Schwann cells associated with nerves that are healthy, but in response to nerve injury CNTF expression decreases in Schwann cells distal to the injury site and remains relatively low unless the injured axon begins to regrow.