The inter-alpha-trypsin inhibitors (ITI) are a family of structurally related plasma serine protease inhibitors involved in extracellular matrix stabilization and in prevention of tumor metastasis. The ITI family contains multiple proteins made up of a light chain and a variable number of heavy chains. By screening a liver expression library with antibodies against ITI chains, Salier et al. (1987) isolated a partial cDNA encoding an ITI heavy chain. Diarra-Mehrpour et al. (1989) analyzed the in vitro translation product of liver mRNAs hybrid-selected by this partial cDNA, lambda-HUHITI(9+33), and determined that it encoded the H2 (ITIH2) heavy chain. Enghild et al. (1989) found that one ITI member is composed of the mature ITIH1 (HC1) and ITIH2 (HC2) heavy chains and a 30kD subunit. Bost et al. (1993) stated that the 30kD subunit is bikunin.