It is highly probable that Notch signaling intermingles with tumor growth and diverts normal cells to an aberrant proliferative cellular pathway, that is, potential targets of this abnormal cellular diversion constitute a group of breast cancers, including EGF receptor- (EGFR-) positive, HER2/erbB2-positive, p53-negative, and estrogen receptor- (ER-) positive and negative cell lines. Here, ESR1 is linked to breast cancer.