In the clinical setting of allogeneic HSCT, donor‐derived NK cells rapidly appeared during immune reconstitution after HSCT and exerted their graft‐versus‐tumor effects both by direct killing of tumor cells and by warning other cells via proinflammatory cytokines such as IFN‐γ and TNF‐α and cytokines such as MIP‐1β13. Here, IFNG is linked to neoplasm.