Endothelial markers are proteins or molecules that are specifically expressed by endothelial cells, which line the interior surface of blood vessels. These markers are important for identifying and studying the function of endothelial cells in various physiological and pathological contexts. Endothelial markers can include proteins such as CD31, CD34, von Willebrand factor, and vascular endothelial growth factor receptor 2 (VEGFR2), among others. Studying endothelial markers can help researchers understand processes such as angiogenesis, inflammation, and vascular permeability, and may have implications for the development of therapies for cardiovascular diseases, cancer, and other conditions that involve endothelial dysfunction.