The role of the EP1 and EP3 receptors in Cox-2-mediated invasion of MCF-7/DOX cells. (A) The expression of EP receptor mRNAs was determined by RT-PCR in MCF-7 and MCF-7/DOX cells. (B) MCF-7/DOX cells were serum starved for 12 h, treated with PGE2 (10 μM) for 24 h, and the expression of EP receptor mRNAs was determined by RT-PCR. (C) MCF-7/DOX cells were transfected with siRNAs specific for EP1 or EP3 and analyzed using cell invasion assays. Cells were treated with PGE2 (10 μM) to activate invasion of MCF-7/DOX cells. (D) Semiquantitative RT-PCR analysis of uPA, MMP-2, and MMP-9 in MCF-7/DOX cells transfected with siRNAs specific for EP1 or EP3. (E) MCF-7/DOX cells were starved in serum-free medium for 18 h and pretreated with 17-PT-PGE2, sulprostone, or PGE2 for 13 h from 1 h before AH6809 treatment (10 μM, 12 h). MMP-2, MMP-9, and uPA expression were determined by semiquantitative RT-PCR analysis.