Fig. 5.
Carvedilol-stimulated ERK 1/2 phosphorylation is abolished by siRNA targeting β-arrestin2. HEK-293 cells stably expressing β2AR (A) or β2ARTYY (B) were stimulated with 10 μM isoproterenol (Iso) or carvedilol (Carv) in the presence of either control siRNA (CTL) or siRNA targeting β-arrestin2 (βarr2) for 5 min, and cell lysates were analyzed for pERK, ERK, and β-arrestin 1/2 by Western blot. Data represent mean ± SE of four independent experiments done in duplicate. Quantification of pERK bands is as a percentage of maximal activity observed for isoproterenol. **, P < 0.01; *** P < 0.001.