NOX4 and heart failure: NOX4 has been previously associated with Hcy in three studies.46–48NOX4 is expressed in endothelial cells, cardiomyocytes, and vascular smooth muscle cells,49 and elevated expressions were reported in patients with hypertension, atherosclerosis, heart failure, and stroke.50 Upregulation of NOX4 may also contributes to Hcy-mediated apoptosis of endothelial cells.51