PTGS2 and breast cancer: Upregulation of cyclooxygenase (COX)-2, an inflammation-associated enzyme, noted in half of the breast cancer patients [1] promotes tumor progression and metastasis through multiple mechanisms, including increased cancer cell proliferation, migration, invasion, epithelial-to-mesenchymal transition (EMT), tumor-associated angiogenesis, lymphangiogenesis, and induction of stem-like cells (SLCs) [2–6].