IFNG and neoplasm: As reviewed in recent articles, NK cells can attack tumor cells not only directly via several mechanisms, including secreting cytoplasmic granules (such as perforin and granzymes), death receptor-mediated apoptosis (such as FasL or TNF-related apoptosis-inducing ligand (TRAIL)), releasing various cytokines (such as IFN-γ) or through antibody dependent cellular cytotoxicity (ADCC) by expressing CD16 antigen on the surface of NK cells (Fig. 1), but they also act indirectly through interaction with other immune cells via production of different cytokines, chemokines and growth factors [41].