CST3 and hepatocellular carcinoma: Human cystatin C (HCC), also known as cystatin 3, post-gamma globulin or formerly as human gamma trace (MW 13,335 Da, 120 amino acids in posttranslational form, UNIPROT entry: P01034), was characterized and identified by Grubb and co-workers as an important protein inhibitor of cysteine proteases [1,2,3].