PTGS2 and neoplasm: The TME is composed of a variety of cells and molecules, including tumor-associated fibroblasts, tumor-associated macrophages, Tregs, immunoregulatory enzymes (e.g., arginase and cyclooxygenase-2 [COX-2]), and immunosuppressors (e.g., interleukin [IL]-10, transforming growth factor-β [TGF-β], vascular endothelial growth factor [VEGF], prostaglandin E2 [PGE2], and programmed death-ligand 1).