In addition, cytokines by themselves are capable of generating memory-like NK cells in an antigen–independent setting (14), as NK cells, shortly cultured in the presence of IL-12, IL-15 and IL-18, showed superior IFN-γ and TNF-α production and cytotoxicity in response to tumor targets and conferred more protection to leukemia or melanoma in xenograft mouse models. This evidence concerns the gene TNF and neoplasm.