Our present findings that the expression of BECN1, ATG5, ATG7, and LC3 as well as the LC3-II/LC3-I ratio, the measure of autophagy flux, are downregulated by Hcy, Hcy-thiolactone, and N-Hcy-protein in HUVEC suggest that impaired autophagy can accelerate endothelial dysfunction and lead to vascular disease. Here, ATG5 is linked to endothelial dysfunction.