DLL4 and neoplasm: In the light of our current results it is tempting to speculate that overexpression of Dll4 in tumour cells adjacent to the endothelium will cause synchronization of endothelial Notch dynamics, similar to the situation of overexpressed endothelial Dll4. Conversely, inhibition of Dll4 by antibody, genetic haploinsufficiency or Notch inhibition by DAPT all lead to a dramatic increase in vessel branching, but reduced vessel diameter in tumour vessels (Ridgway et al., 2006; Noguera-Troise et al., 2006).