Background: HABP2 is an extracellular serine protease that binds hyaluronic acid and is involved in cell adhesion. The encoded protein is synthesized as a single chain, but then undergoes an autoproteolytic event to form the functional heterodimer. Further autoproteolysis leads to smaller, inactive peptides. This protease is known to cleave urinary plasminogen activator, coagulation factor VII, and the alpha and beta chains of fibrinogen, but not prothrombin, plasminogen, or the gamma chain of fibrinogen. Two transcript variants encoding different isoforms have been found for this gene.