NOS2 and melanoma: Several studies have reported constitutive iNOS expression in A375 melanoma cells and in A375-derived xenograft tumors, as well as in primary patient-derived melanoma tissues (Ekmekcioglu et al., 2006; Uffort et al., 2009; Sikora et al., 2010; Godoy et al., 2012; Lopez-Rivera et al., 2014).