DLL4 and ischemia: Given the rising interest and often conflicting data on the role of Dll4/Notch signaling in promoting vessel maturation 27, 28, 29, 30 and our own experience researching the role of Dll4 in regulating vascular permeability and intercellular communication,14 we also tested how Dll4/Notch signaling affected recovery of blood flow after ischemia.