We have previously shown that vessels in DLL4-overexpressing U87 xenografts are larger, better perfused and the tumours less hypoxic, due to increased NOTCH1 signalling in the vasculature.14 These xenografts were chosen to study tumour endothelial FABP4 expression in response to NOTCH1 signalling and NOTCH1/ VEGFA-targeting therapies in vivo. The gene discussed is VEGFA; the disease is neoplasm.