WAS and T-cell non-Hodgkin lymphoma: To address the role of NK cell-mediated tumor rejection in WASp KO mice, we performed a competitive assay in which we injected T cell lymphoma cells expressing MHC class I (RMA) or with reduced expression of MHC class I (TAP−/−; RMA-S), labeled with different concentrations of CFSE (Fig. 1C).