Fig. (1) Both G-protein and β-arrestin mediated signaling pathways can lead to ERK activation. However, the subcellular distributions of activated ERK1/2 are different. The phosphorylated ERK1/2 mediated by the β-arrestin signaling pathway largely remain in cytoplasm, while the phosphorylated ERK1/2 mediated by the G-protein signaling pathway translocate to the nucleus.