The role of Cox-2 in invasiveness of MCF-7/DOX cells. (A) Western blot analysis of Cox-2 expression in MDA-MB-231, MCF-7, MCF-7/DOX, and T-47D cells. (B) Invasion assay with MCF-7/DOX cells treated with 50 μM NS398 for 18 h. (C) The effect of NS398 on uPA, MMP-2, and MMP-9 activity in MCF-7/DOX cells was determined by gelatin or fibrinogen/plasminogen zymography. (D) Cell proliferation in MCF-7 and MCF-7/DOX cells treated with the indicated concentrations of NS398 for 72 h. *P < 0.01. (E) A cell migration assay with MCF-7/DOX cells transfected with Cox-2-specific siRNA.