PSMB4 and amyotrophic lateral sclerosis: Proteomics data suggested that disturbances in protein homeostasis and abnormal proteolysis through the ubiquitin–proteasome and/or endosome–lysosome systems occur in ALS astrocytes, where a higher abundance of the non-ATPase regulatory subunit 8 (PSMD8) and of subunit β4 of the 20S catalytic core (PSMB4) of the 26S proteasome was found compared to non-ALS controls.