Fig. 2.

H₂O₂ increases CREB-Ser¹³³ phosphorylation without increasing CRE-luciferase activity in cardiomyocytes. A, cardiomyocytes were treated with vehicle, H₂O₂ (50 μM), or forskolin (10 μM) for indicated time intervals, and cell extracts were subjected to Western blotting with indicated antibodies. B, the CRE-firefly luciferase reporter construct and a R. reniformis luciferase vector (included as an internal control to normalized for differences in transfection efficiency) were introduced into cardiomyocytes by electroporation. Cells were treated with vehicle, H₂O₂ (0.05 mM), or forskolin (Fors, 10 μM, as a positive control) for indicated intervals, and CRE-firefly luciferase activity was corrected for minor differences in R. reniformis luciferase activity (n = 4). *, p < 0.05 versus control.