Nevertheless, reports of low level NKG2D-ligand expression in gut epithelium (35, 36), the possibility of NKG2D-ligand-upregulation in healthy tissues under conditions of cell stress and infection (19) and dose-dependent toxicity observed in mouse models (37, 38) were of potential concern for the translation of this approach into the clinic (39). The gene discussed is KLRK1; the disease is infection.