However, the use of GSIs in murine model of GvHD is associated with a severe toxicity in the gut epithelium (29); (2) monoclonal antibodies directed against NOTCH ligands such as Dll1–4 (29); (3) we recently identified the calcium channel modulator bepridil as a new NOTCH1 pathway inhibitor in Chronic Lymphocytic Leukemia (40). The gene discussed is DLL1; the disease is graft versus host disease.