ARG1 and neoplasm: Mechanistically, recruited neutrophils express inducible nitric oxide synthase(iNOS) and arginase 1 (ARG1) to inhibit activation and anti-tumor effects of CD8 + T cells (12, 21–23), produce reactive oxygen species (ROS) or reactive nitrogen species (RNS) to facilitate the transformation of epithelial to cancer cells, and induce BV8 and vascular endothelial growth factor (VEGF), leading to remodeling of extracellular matrix (ECM) and mediation of angiogenesis (22, 23).