GDNF and amyotrophic lateral sclerosis: Some of the agents that have been shown to slow the onset or prolong the course of ALS in SOD mutant mouse models, include cyclooxygenase 2 inhibitors [32], insulin-like growth factor (IGF1) [33], certain neurotrophic factors such as BDNF (brain derived neurotrophic factor) and GDNF (glial derived neurotrophic factor) [34], and VEGF (vascular endothelial growth factor) [35].