Our previous studies demonstrated that a portion of ES tumor vascular pericytes are derived from bone marrow progenitor cells [22], that VEGF165 was involved in the chemoattractant recruitment of these bone marrow cells to the tumor for formation of new blood vessels, and that the Notch-DLL4 signaling pathway regulated their differentiation into vascular pericytes [19,20,21]. Here, DLL4 is linked to neoplasm.