Interestingly, in σ1R KO mice, spinal cord pERK1/2 remains unchanged following SCI, which would agree with the reduced mechanical and thermal hypersensitivity in these mice lacking σ1R. Previous studies also reported no changes in spinal pERK1/2 expression in peripheral nerve-induced or inflammatory pain models in σ1R KO mice: phosphorylation of ERK was increased in the ipsilateral spinal hemicord of WT mice but not in σ1R KO mice after partial sciatic nerve ligation12; and paclitaxel treatment induced peripheral neuropathy associated with pERK increase in WT but not in σ1R KO mice28. This evidence concerns the gene EIF2AK3 and peripheral neuropathy.