Fig. 4.

Effect of Rab2 and Rab6 on signaling of α_2B-AR and β₂-AR. A. Effect of Rab2 and Rab6 on ERK1/2 activation by α_2B-AR. HEK293T cells were transfected with GFP-tagged α_2B-AR together the pEGFP-C1 vector (GFP), GFP-Rab2Q65L, the pcDNA3 vector, FLAG-Rab6Q72L, Rab2 control siRNA, Rab2 siRNA, Rab6 control siRNA or Rab6 siRNA as described under “Experimental procedures”. The cells were stimulated with UK14304 at a concentration of 1 µM for 5 minutes at 37 °C. ERK1/2 activation was determined by Western blot analysis using phospho-specific ERK1/2 antibodies (ERK1/2-P). upper panel, representative blots of ERK1/2 activation; lower panel, total ERK1/2 expression. B. Quantitative data expressed as percentages of ERK1/2 activation obtained from cells transfected with α_2B-AR and a separate control and stimulated with 1 µM UK14304 and presented as the mean ± S.E. of three experiments. C. Effect of Rab2 and Rab6 on cAMP production by the β₂-AR agonist ISO. HEK293T cells were cultured in 100-mm plates and transfected with β₂-AR as described in (A) for α_2B-AR and then stimulated with ISO (10 µM) for 10 minutes. cAMP concentrations were determined by using cAMP enzymeimmunoassay system as described under “Experimental procedures.” The data are presented as fold increase in response to ISO stimulation over the basal values and as the mean ± S.E. of three experiments. *, p < 0.05 versus their respective controls.