NOS2 and neoplasm: Alternately activated macrophages or M2-type macrophages promote immunosuppression and are characterized by decreased iNOS and TNF-α expression, and positively influence tumor growth, metastases, angiogenesis, and extracellular matrix remodeling, while classically activated or M1-type macrophages exhibit phagocytic activity, can promote a Th1 response, and are associated with tumor growth suppression [10, 14, 15].