The proteolysis of extracellular matrix is an important biochemical process of the malignant tumor cells. The ability of invasion of tumor cells is related to the activity of plasminogen activator. We constructed an expression vector of PAI-2 cDNA, and transfected it into HT1080 C + tumor cell. The recombinant PAI-2 could inhibit the activity of plasminogen activator on the cell surface and subsequently inhibit the degradation of extracellular matrix by tumor cells. The extracellular matrix degradation by C + e x p cell is about 13.5% by C + cell.