SMN1 and amyotrophic lateral sclerosis: In particular, the regulation of actin dynamics at the synapse, which is accomplished by a plethora of actin-binding/-regulating proteins is crucial for the proper function and maturation of neuromuscular junctions (NMJs), that are supposed to be a primary, early target of both ALS and SMA (Fischer et al., 2004; Kariya et al., 2008).