To determine the effect of Notch-1 signaling on human breast cancer, human breast cancer cell line, MDA-MB-231, was employed as a model system to simulate gain of functions by forced expression of a plasmid encoding human Notch-1 intracellular domain (NICD) or loss of functions by knockdown its expression with Notch-1 shRNA respectively. Here, NOTCH1 is linked to breast cancer.