GDNF and amyotrophic lateral sclerosis: Protective effects of growth factors, such as CNTF (ciliary neurotrophic factor), GDNF (glial cell line-derived neurotrophic factor), IGF-1 (insulin-like growth factor 1), FGF2 (basic fibroblast growth factor 2) and VEGF (vascular endothelial growth factor) [26], [27], [28], [29], [30] have been shown in rodent models of ALS.