NOS2 and neoplasm: M2-polarized TAMs play a crucial role in tumor progression through the several mechanisms: (i) immunosuppression and release of anti-inflammatory cytokines; (ii) shaping of tumor-promoting microenvironment through the production of survival/growth factors, such as VEGF; (iii) release of proangiogenic factors (MMP-2/-9 and COX-2); and (iv) increase in the activity of arginase (Arg) and decrease in the activity of inducible nitric oxide synthase (iNOS).