DLL4 and nasopharyngeal carcinoma: Similarly, high expression of Dll4 by endothelial cells was shown to be a statistically significant adverse prognostic factor in breast and ovarian cancer patients [20], [21]; and elevated expression of both DLL4 and VEGF was found to be a significant overall survival disadvantage in nasopharyngeal carcinoma patients, as compared to those with dual low expression [22].