This degeneration was restricted to CSMNs since analysis of callosal projection neurons (CPNs), which are developmentally closely related to CSMN but less vulnerable in ALS, showed that staining with CPN-specific markers LIM domain only four (LMO4) and special AT-rich sequence-binding protein 2 (SATB2), did not differ between WT and Sod1D83G/D83G littermates, at either age (Supplementary Material, Fig. S2C and D). This evidence concerns the gene SATB2 and amyotrophic lateral sclerosis.