GDNF and amyotrophic lateral sclerosis: For example, GDNF-fragment C promotes neuronal survival and neurite outgrowth in animal models of Parkinson’s disease [66] and amyotrophic lateral sclerosis (ALS) [67,68], and BDNF-fragment C is protective in a mouse model of ALS, although no synergistic effect of this recombinant molecule was found [69].