PRKN and amyotrophic lateral sclerosis: In the presence of NMN, axons from PARK2 PD and TDP-43N390D ALS neurons displayed a 1.6-fold increase in cGFP fluorescence recovery compared to untreated controls (Figs. 7, A and B, and 8, A and B) and a significant increase in their mobile fraction (Figs. 7C and 8C).