Since we have reported that i21VEGFR-1 can activate Src and increase the invasiveness of MDA-MB-231 cells [23], Notch-1 and Notch-3 signaling pathways could contribute to the invasive phenotype of MDA-MB-231 breast cancer cells through upregulation of i21VEGFR-1 protein. The gene discussed is NOTCH3; the disease is breast cancer.