Our results demonstrate that downregulation of uPAR expression by an antisense approach in a colon cancer cell line was associated with a two-fold inhibition of Erk-MAP kinase pathway, inhibition of uPA secretion, complete inhibition of pro-MMP-9 secretion, 1.3-fold inhibition in adhesion, four-fold inhibition in migratory/invasive capacity and complete abrogation of plasmin-dependent matrix degradation. This evidence concerns the gene MMP9 and colonic neoplasm.