PSMB9 and polymyositis: For example, increased mRNA and protein expression of IMP subunits (PSMB8, PSMB9, and PSMB10) has been detected in muscle biopsies and peripheral blood cells of patients with polymyositis, dermatomyositis, and overlap-syndromes with myositis compared to those with non-inflammatory myopathies and healthy donors [29].