Nerve fibroblasts and Schwann cells play an important role in increased expression of NGF mRNA.[24] Macrophages also stimulate Schwann cells and fibroblasts to produce NGF via macrophage-derived interleukin-1.[25] Other neurotrophic molecules produced by Schwann cells and fibroblasts together include Brain-derived neurotrophic factor, Glial cell line-derived neurotrophic factor,Ciliary neurotrophic factor, Leukemia inhibitory factor, Insulin-like growth factor, and Fibroblast growth factor. These factors together create a favorable environment for axonal growth and regeneration.[3] Apart from growth factors, Schwann cells also provide structural guidance to further enhance regeneration.