Recent studies have found other E3 ligases that are upregulated with MuRF-1 and Atrogin-1 to promote atrophy, which could be of interest in SMA given the fact that the inhibition of MuRF1 and Atrogin-1 does not rescue the SMA phenotype in the SMNΔ7 SMA mouse [99]. This evidence concerns the gene FBXO32 and proximal spinal muscular atrophy.