stromal expression of mmp9 and urokinase receptor is inversely associated with liver metastasis and with infiltrating growth in human colorectal cancer a novel approach from immuneinflammatory aspect mmp9 gelatinase b and urokinasetype plasminogen activator receptor upar which are involved in cancer cell invasion and metastasis are reported to be predominantly expressed by immuneinflammatory cells in human colorectal cancers to investigate their significance in cancer progression we morphometrically analyzed the tissue expression of mmp9 and upar among different stages of colorectal cancer the numbers of mmp9 and uparpositive cells along the invasive margin were significantly smaller in cases with liver metastasis than in cases without liver metastasis and were also smaller in cases with an infiltrating margin than in cases with an expanding margin both variables were larger in colon cancer cases with conspicuous lymphocytic infiltration these results indicated that the degree of tissue expression of mmp9 and upar by host cells is inversely associated with liver metastasis and an infiltrating growth pattern in human colorectal cancers essentially the same results were obtained for the number of macrophages distributed along the invasive margin we also found that the expression pattern of mmp9 was similar to that of mmp8 polymorphonuclear leukocyte collagenase these data are consistent with clinicopathologic studies of host cells therefore our data suggest a dual role of mmp9 and upar expression in colon cancer tissue ie not only are these proteinases cancerpromoting factors but also they are related to the host defensive mechanism when they are expressed by host cells