Zhu et al. reported that deletion of cytokine-inducible SH2-containing protein (CIS; encoded by the gene CISH) in human iPSC-derived NK cells promoted the expansion of NK cells and increased the cytotoxic activity against multiple tumor cell lines when maintained at low concentrations of cytokine interleukin-15 (IL-15) (Figure 2) [26]. This evidence concerns the gene CISH and neoplasm.