FASLG and neoplasm: NK cells are components of the innate immune system and have an important role in the antitumour response, based on several of their functions: (i) their cytolytic activity via the release of perforin and granzyme; (ii) inducing apoptosis in target cells via the production of TNF; (iii) inducing apoptosis via cell–cell contact and activation of the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) and Fas ligand (FASL) pathways [41,42]; and (iv) killing tumour cells coated with antibodies via antibody-dependent cell-mediated cytotoxicity (ADCC) [43].