Fig. 2. Representative Western blots of concentration-dependent increased protein expression of heme oxygenase 1 (HO-1) and manganese superoxide dismutase (MnSOD) in human umbilical vein endothelial cells (HUVECs) and human endothelial progenitor cells (EPCs) 12 h after exposure to hemin (0–50 μm). EPCs were isolated from human blood and analyzed 7 days after plating in endothelial growth medium 2. Experiments were performed in blood samples obtained from three independent healthy human volunteers (EPCs) and two different sources of HUVECs.