Histologicaly, Dll4 overexpression in RT2 D4OE mice was found to decrease insulinoma endothelial density by 32% (p < 0.05; Fig. 5d,e), increase α-SMA-positive mural cell coverage by ~20% (p < 0.05; Fig. 5d,f) and result in improved lectin perfusion by 27% (p < 0.05) in relation with RT2 D4BE insulinomas (Fig. 5g,h). The gene discussed is ACTA1; the disease is pancreatic insulinoma.