KDR and coronary artery disorder: In diabetic patients with chronic coronary heart disease, myocardial biopsies have revealed significantly higher levels of VEGF mRNA and protein compared to non-diabetic CHD patients; however, these patients often exhibit paradoxically lower expression and phosphorylation (activation) of VEGFR-2 (Flk-1), suggesting receptor downregulation or desensitization despite high ligand levels [207].