As the Notch ligands Jagged1 and Dll4 promote angiogenesis in several cancers, including breast cancer [40, 41] and increased angiogenesis is associated with increased metastasis in cancer [42], we next assessed the expression of CD31 and CD34, both of which are used to measure angiogeneic blood vessels in tumors. The gene discussed is DLL4; the disease is breast cancer.