To further identify which signal transduction pathway(s) was involved in the mechanism behind PGE2-upregulated expression of uPA and MMP-9 in human colon cancer cells, we applied the following inhibitors such as LY294002 (Akt activation inhibitor), U0126 (ERK1/2 activation inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor), and QNZ (NFκB activation inhibitor) to respectively block these pathways, followed by the administration of PGE2. The gene discussed is MAPK3; the disease is malignant colon neoplasm.