NOS2 and neoplasm: M1 macrophages are induced by inflammatory stimuli, such as lipopolysaccharide (LPS), and are characterized by the production of high levels of proinflammatory cytokines, including, interleukin (IL)-1β, IL-12, and tumor necrosis factor (TNF)-α, inducible nitric oxide synthase, (iNOS), reactive oxygen species (ROS), and suppression tumor cell growth7, 8.