One of the key questions in tumor immunobiology is whether constitutively expressed iNOS in cancer cells produces functionally active NO at levels comparable to those generated by inducible iNOS in activated macrophages (Uffort et al., 2009; Sikora et al., 2010; Godoy et al., 2012; Lopez-Rivera et al., 2014). The gene discussed is NOS2; the disease is neoplasm.