KDR and chronic kidney disease: There were no significant differences in controls and CKD patients by staining for VEGF-A (0.41% vs. 0.44%; p = 0.70) or the intracellular domain (0.43% vs. 0.67%; p = 0.61) or extracellular domain (0.43% vs. 0.3%; p = 0.78) of the VEGF receptor 2 (Flk-1/KDR) when examined with specific antibodies against either domain (Figs 4 and 5).