PSMB9 and peeling skin syndrome: Dysregulated expression of the proteasomal subunits β5i and β1i (PSMB9, also known as LMP2) in peripheral leukocytes and in inflammatory infiltrates of salivary gland tissue in patients with pSS has been reported in several studies (49–52), suggesting the immunoproteasome as a potential drug target (53, 54).