FOXO1 and ischemia: Indeed, Sirt-1 is involved in angiogenic process, as mice displaying endothelial cell-specific deletion of SIRT1 present an impaired angiogenesis in response to ischemia due to its ability to deacetylate forkhead transcription factor Foxo1, an essential negative regulator of blood vessel development, to restrain its anti-angiogenic activity [35].