DLL4 and neoplasm: Similarly to Vegf-a, Vegf-c, a positive driver of normal lymphangiogenesis and an additional tumor pro-angiogenic factor [41], was also found up-regulated possibly due to more pronounced hypoxia while Dll4 overexpression in tumor endothelial cells decreased receptor Vegfr3 levels and, thereby, tumor vascular sensitivity to VEGF-C.