Concurrent with an increase in LMP2 and LMP7 expression, an increase in trypsin- and chymotrypsin-like activity was observed in HD brains in the areas most affected (Diaz-Hernandez et al., 2003), and in PD brains, an increase in expression of immunoproteasome subunit LMP7 (β5i) was observed (Ugras et al., 2018). Here, PSMB8 is linked to Parkinson disease.