Expression and activity of HO-1 induced by VEGF in human ECs. Lysates were prepared from HMECs and HUVECs treated with VEGF (25 ng/mL) or aFGF (100 ng/mL) for up to 48 hours and proteins were separated by SDS-PAGE and transblotted on to nitrocellulose membranes. Immunoblots were probed with a polyclonal Ab against HO-1 and mAb C-2 against actin as a loading control. (A) HMECs and (B) HUVECs. Lane 1, unstimulated ECs; 2, VEGF 24 hours; 3, VEGF 48 hours. (C) HMECs. Lane 1, unstimulated ECs; 2, aFGF 24 hours; 3, aFGF 48 hours. (D) Heme oxygenase activity was measured in lysates of HMECs cultured in the presence or absence of VEGF (25 ng/mL) for 24 hours. Data presented as mean ± SEM.