Anti-Cystatin A antibodies are used in the immunodetection of the protein encoded by the CSTA gene. In humans, the canonical protein has a reported length of 98 amino acid residues and a mass of 11 kDa. Its subcellular localization is in the cytoplasm. It is reported to be expressed in the skin throughout the epidermis. A member of the Cystatin protein family, it is an intracellular thiol proteinase inhibitor. Other names for this target antigen include PSS4, STF1, STFA, cystatin A (stefin A), cystatin AS, and AREI.