In the TME, MDSCs secrete soluble factors such as arginase1 (ARG1), inducible NO synthase (iNOS), nitric oxide (NO), ROS, transforming growth factorβ (TGFβ), adenosine, IL-10, and PGE2 to inhibit T cells and NK cells activity, and suppress antitumor immunity, leading to tumor progression [2,23]. Here, NOS2 is linked to neoplasm.