Tumor-induced dysregulation of Notch was confirmed in mice bearing tumor models such as breast adenocarcinoma 4T1HA, renal carcinoma RencaHA and lung fibrosarcoma D459, which showed downregulation of Notch receptors, Notch1, Notch2, Notch3 and Notch4 as well as Notch ligands, Dll1, Dll4 and Jagged1 in their lymphoid organs. This evidence concerns the gene JAG1 and breast adenocarcinoma.