These macrophages are classified as M1 or classically activated macrophages and can exert an anti-tumor effect through the production of high levels of proinflammatory cytokines, such as interleukin (IL)-12 and tumor necrosis factor (TNF)-α, as well as radical oxygen and nitrogen species, such as nitric oxide (NO), which is produced by the enzyme inducible nitric oxide synthase (iNOS). Here, NOS2 is linked to neoplasm.