A mixture of three cell lines was injected i.p.: RMA, a MHC class I-bearing lymphoma that is resistant to NK cell cytotoxicity; RMA/S, a MHC class I-negative variant of RMA that is susceptible to NK cell-mediated cytotoxicity and rejection, independently of NKG2D; and Rae1-RMA, a RMA cell line transduced with Raet1e. This latter modification makes it susceptible to NKG2D-dependent NK cell cytotoxicity (27). The gene discussed is KLRK1; the disease is lymphoma.