Fig. S1.

In cells treated with siRNAs targeted to β-arrestin1 (Middle) and β-arrestin2 (Bottom), ICL1–9-promoted ERK1/2 phosphorylation (blue) is dependent on β-arrestin expression. Interestingly, siRNA treatment targeting β-arrestin1 and β-arrestin2 also reduced the burst and sustained phase of isoproterenol-promoted ERK1/2 phosphorylation (red). The blots are representative of three independent experiments and the plot represents the quantitated mean ± SD from three independent experiments. The ICL1–9 results are identical to those shown in Fig. 4B.