KLRK1 and neoplasm: Similarly, to our assessment of intracellular IFN-γ production, NKG2D-CAR T cells secreted robust levels of IFN-γ in the presence of NKG2D-ligand tumor cell targets, whereas no significant IFN-γ production was detected when T cells were cultured alone or with the control cell line B16 (Figure 4E).