PECAM1 and neoplasm: We confirmed that Notch3 is expressed in the vasculature of the grafted tumours and as observed in the tumour nodules from the Kras+/G12D mice, we observed an aberrant expression of Notch3 in tumour-associated EC (Fig. 1d,e): Notch3 co-localizes with CD31 (endothelial cell marker platelet/endothelial cell adhesion molecule, PECAM-1) but not with mural cell markers αSMA or NG2 (Fig. 1d).