SMN is associated with hnRNP-R, Zbp1, eEF1A, profilin II and β-actin mRNA and motoneurons isolated from severe SMA mice show a reduction of hnRNP-R, β-actin mRNA, and actin protein in the distal axons and growth cones, suggesting a role in local protein synthesis and actin dynamics in neurons (reviewed in [116]). Here, SMN1 is linked to proximal spinal muscular atrophy.