PTGS2 and breast cancer: We validated this contention in a high COX-2 expressing syngeneic murine breast cancer model, in which therapy with a COX-2 inhibitor or two EP4 antagonists, equally inhibited tumor growth, tumor-associated angiogenesis and lymphangiogenesis and metastasis to the lymph nodes and the lungs [27], and were also SLC-reductive in vivo [25].