Ni et al., using a mouse model with the conditional deletion of HIF-1α in NK cells, elegantly demonstrated that lack of HIF-1α renders certain NK cells capable of producing IFN-γ in response to IL-18 in the tumor hypoxic environment and that these HIF-1α−/− NK cells can infiltrate and control the tumor in vivo [47]. The gene discussed is IL18; the disease is neoplasm.