CDK5 and atherosclerosis: Previous studies have shown that SIRT1 expression is reduced in the primary senescent porcine aortic endothelial cells and human atherosclerotic plaques (Menghini et al., 2009; Bai et al., 2012; Gorenne et al., 2013), and CDK5-mediated hyperphosphorylation of SIRT1 decreases its deacetylase activity and facilitates the development of endothelial senescence and atherosclerosis (Bai et al., 2012).