Fig. 3

The β-ARs desensitization by isoproterenol. a Phosphorylation of β1-AR by ISO through GRK2 and PKA. The experimental data were obtained from Freedman et al.’s study [21] for HEK293 cells with and without PKA inhibitor (H89) after 3-min ISO stimulation. b Desensitization of β2-AR by ISO after different ISO concentration and stimulation times. The experimental data were obtained from Lohse et al.’s study [36] for A431 cells with and without PKI (1 µM). The experimental data are mean ± SE of at least three independent experiments