DPP4 and synovial sarcoma: A recent study that evaluated human salivary proteases in Sjögren’s syndrome (SS), an autoimmune exocrinopathy characterized by progressive damage to the salivary and lacrimal glands associated with lymphocytic infiltration, found increased activity of human sDPP4/CD26 in SS saliva [145] and obese adults [146], although it might have specificity problems in patients with periodontitis [147,148].