Fig. 3.

Stable expression of a phosphorylation-independent mutant β-arrestin2 (R169E) prevented the prolonged PTH activation of ERK1/2 in the PD-PPR cells. The WT-PPR and PD-PPR cells stably expressing β-arrestin2 (R169E) were serum starved for 1 h and then treated with vehicle or 10 nM PTH for 10–120 min at 37°. The cells were then processed and analyzed for ERK1/2 activation as described in Fig. 1 (blots on top). The blots were stripped and reprobed with anti-total ERK1/2 antibody as described above (blots on bottom). Representative images are displayed from one experiment. The respective graphs represent Western blot band densities of the 42-kDa P-ERK relative to its own T-ERK. The graphs are representative of results from 4 independent experiments; all experiments were performed in the GFP-tagged PPR cell lines. The data are expressed as means ± SD. Bars with * or ** indicate a P < 0.05 compared with its own vehicle control.