DLL4 and hereditary elliptocytosis: Activation of NOTCH signaling through immobilized NOTCH-ligand DLL1-Fc in CD31+ (PECAM1, an endothelial-specific marker) cells led to the upregulation of typical NOTCH-downstream genes (HES1) and expression of typical arterial-associated genes (e.g., DLL4, EFNB2, HEY2, SOX17, and CXCR4) in a transient, CD144+/CD73−/CD43−/DLL4+ HE population.