Alpha-1-Antichymotrypsin (SERPINA3) [AACT/1451]

Alpha-1-Antichymotrypsin (ACT) is a serine protease inhibitor. It forms a complex with serine protease, a prostate-specific antigen in human serum. ACT can be found in most cells of myeloid lineage and is, therefore, useful in the identification of neoplastic myeloid cells within extramedullary tissues such as acute myeloid leukemia. This enzyme is also localized in the spindle cells and round cells of true histiocytic lymphomas as well as in most thyroid papillary carcinomas. ACT is expressed in various normal and neoplastic cells.