Classically activated M1 Mφs are efficient at phagocytosis and killing pathogens at sites of infection, by upregulation of inducible nitric oxide synthase (iNOS) and subsequently nitric oxide (NO) production in response to inflammatory cytokines (Sheel and Engwerda, 2012; Ginhoux and Guilliams, 2016). This evidence concerns the gene NOS2 and infection.