In breast cancer, abnormal functioning of different signaling pathways such as HER2, PI3K/AKT, TP53, MAPK, mTOR, Notch-1, Hedgehog, Wnt/β-catenin, and STAT3 have been found to be involved in tumorigenesis, tumor maintenance, drug resistance, and relapse [12,13]. This evidence concerns the gene NOTCH1 and breast cancer.