CSF2 and neoplasm: Indirect mechanisms by which NK cells induce anti‐tumour activity include the release of proinflammatory cytokines, including interferon (IFN)‐γ, tumour necrosis factor (TNF)‐α and granulocyte macrophage colony‐stimulating factor (GM‐CSF), favouring the recruitment of CTL and phagocytic cells (Fig. 1b) [22, 23].