Orthotopic mammary tumors that were grown with MCF-7-COX-2 cells (as compared to control cells) showed an up-regulation of angiogenic/lymphangiogenic factors VEGF-A/C/D, Vimentin (mesenchymal marker), and phospho-AKT (an EP4 signaling marker), down-regulation of epithelial marker E-Cadherin and an enrichment of SLC marker positive and spheroid forming cells. This evidence concerns the gene PTGER4 and breast cancer.