SMN1 and spinal muscular atrophy, type 1: In C2C12 myoblasts, we identified a significant upregulation of only the FoxO3 gene in Smn-depleted C2C12 myoblasts compared to controls (Fig. 5a), which reflects previous microarray analyses of specific FoxO isoforms upregulated in quadriceps femoralis muscle biopsies from Type 1 SMA patients [66].