Cystatin SA is a member of family 2 of the Cystatin superfamily. Together with Cystatins S and SN, it is produced by the salivary gland and secreted largely in the submandibular/sublingual saliva. Cystatin SA inhibits Cathepsin L, but may not inhibit Cathepsins B and H. The functions of Cystatin SA are largely unknown. However, it has been suggested to play a role in the control of periodontal tissue destruction.