CTSS and amyotrophic lateral sclerosis: The increase in expression of cathepsin transcripts is in keeping with several previous studies which reported increased expression in glia (Fukada et al., 2007) and decreased expression in motor neurons in SOD1-ALS (Wootz et al., 2006; Cox et al., 2010; Kirby et al., 2011), suggesting up-regulation of the lysosomal pathway is astrocyte-specific.