TP53 and proximal spinal muscular atrophy: While the c-Jun N-terminal kinase (JNK)/c-jun signaling axis and the p53 signaling pathway have been implicated in severe SMA mouse models [128,129,130], the molecular mechanisms carrying out spinal motoneuron loss in SMA are likely complex, potentially context dependent, and may differ based on disease severity of the SMA model [131,132].