To determine whether we could promote more efficient generation of angiosarcomas, we directly induced expression of mutant p53 or loss of p53 in adult endothelial cells using Cdh5-CreERT2 mice, in which Cre recombinase is driven by Cdh5. Using Ai14;Cdh5-CreERT2 reporter mice we found that Cdh5-Cre induced recombination in CD31-positive endothelial cells (Fig. S2). Here, PECAM1 is linked to angiosarcoma.