In analogy to the previous gel-based survey of the WR and SOD mouse models of ALS, using fluorescence 2D difference in-gel electrophoresis [39,40], we have used here a complementary gel-free method, i.e. label-free MS, to determine secondary changes in WR skeletal muscle tissue due to abnormal expression of the GARP component VPS54. This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.