CDKN1A and diabetes mellitus: In contrast, diabetic hearts contain only a minor component of epithelial cells (in valves, vessel linings and epicardium) and the majority of cardiac cells (myocytes, endothelial cells, fibroblasts) are less susceptible to diabetes-induced senescence, as indicated by a lack of increase in Cdkn1a and Cdkn2a gene expression in diabetic hearts.