NOS2 and infection: Infection by S. enterica Typhimurium in the tumor microenvironment alerts the immune system, activating oncolytic mechanisms such as increased expression of interferon γ, inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), and tumor necrosis factor α (TNF-α) [10], as well as decreased levels of transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and anti-inflammatory cytokines.