Notch-1, -3, or -4 have shown oncogenic activity in T cell acute lymphoblastic leukemia (T-ALL) (65), B-cell lymphoma (66), cervical (67), colon (68, 69), lung (70), and ovarian (71, 72) cancers while, surprisingly, Notch-2 has displayed tumor suppressive activity in some breast cancer subtypes (73–75). Here, NOTCH1 is linked to breast cancer.