RPS6 and proximal spinal muscular atrophy: While the levels of phosphorylation of 4E-PB1 ans S6 proteins were the same between control and SMA, we found that the GKT137831 treatment promoted the phosphorylation of 4E-PB1 protein, but not of S6 protein, which activation profile remained unchanged compared to vehicle-treated severe type SMA-like mice mouse spinal cord.