Cystatin-A is a member of the cystatin protein superfamily. Cystatin-A is an intracellular thiol proteinase inhibitor which targets members of the cathepsin family, papain, and actinidin. Increased serum levels are seen in lung, head and neck, colorectal and hepatocellular cancers. Increases correlate with lessened metastatic potential and a more favorable patient outcome. Cystatin-A is also upregulated in COPD and liver cirrhosis.
Swiss-Prot Accession Number: P01040