PTGS2 and neoplasm: MDSCs facilitate tumor invasion and metastasis, predominantly through factors like Indoleamine 2,3-dioxygenase (IDO), Arginase-1 (ARG1), Reactive Oxygen Species (ROS), IL-10, Inducible Nitric Oxide Synthase (iNOS), Cyclooxygenase-2 (COX-2), and Nitric Oxide (NO) (69).