Anti-Cystatin E/M antibodies are used in the immunodetection of the protein encoded by the CST6 gene. In humans, the canonical protein has a reported length of 149 amino acid residues and a mass of 16.5 kDa. It is known to be a secreted protein. A member of the Cystatin protein family, it is known to be involved with the morphogenesis of anatomical structure and epidermis development. Post-translational modifications have been described, including glycosylation. Other names for this target antigen include cystatin-M, cystatin 6, cystatin M/E, cystatin-E, cysteine proteinase inhibitor, and ECTD15.