Serpin D1 is also known as Heparin cofactor 2 (HCF2), Protease inhibitor leuserpin-2 (HLS2), Heparin cofactor II (HC-II), which belongs to the serpin family. HCF2 is expressed predominantly in liver. Thrombin inhibitor activated by the glycosaminoglycans, heparin or dermatan sulfate. In the presence of the latter, SerpinD1 / HC-II becomes the predominant thrombin inhibitor in place of antithrombin III (AT-III). In a glycosaminoglycan-independent manner, serpinD1 / HC-II also inhibits chymotrypsin. Peptides at the N-terminal of HC-II have chemotactic activity for both monocytes and neutrophils.