ACVRL1 and diabetes mellitus: Next, as we have previously shown that Alk1 expression is reduced in the pulmonary and retinal endothelium of diabetic mice17, we also evaluated Alk1 expression in the glomerular endothelium in C57BL/6 J mice eight weeks after the onset of STZ-induced diabetes and in renal biopsies obtained from diabetic nephropathy patients.