DLL4 and neoplasm: Of note, analysis of the tumor vasculature revealed that the combination treatments produced decreases in microvascular densities similar to or exceeding the anti-vascular effects observed for the VEGF pathway targeting agents alone, suggesting that in the models analyzed in this study, the anti-VEGF vascular ‘pruning’ effects were dominant over the endothelial hypersprouting phenotype associated with Dll4 blockade.