M1 macrophages are also responsible for NO production [267], causing cell cycle arrest and tumor cell cytostasis or apoptosis, and further sensitizing cancer cells to TNF-induced cytotoxicity. On the contrary, macrophages conditioned by anti-inflammatory cytokines released in tumor microenvironment—such as IL-4, IL-10, amongst others—polarize towards the M2 phenotype [268]. This evidence concerns the gene IL4 and neoplasm.