Figure 5.

Co-application of isoprenaline (ISO) and WIN results in an additive increase in ERK phosphorylation. (A) Dose–response curves for pERK activation following co-exposure of isoprenaline and 0.05% DMSO vehicle, 0.1 µM WIN or 0.3 µM WIN in CB₁-GFP²/TreHA-β₂AR pretreated for 24 h with 10 µg·mL⁻¹ Dox; n= 6. (B) pCREB responses in CB₁-GFP²/Tet-ON/HA-β₂AR cells pretreated for 24 h with Dox (10 µg·mL⁻¹) then co-exposed to isoprenaline (0, 1 and 10 nM) and DMSO vehicle (0.05%), WIN (1.0 µM) or forskolin (10 µM). *P < 0.05, ***P < 0.001 compared with DMSO, or isoprenaline alone groups, respectively; n= 10–28. CREB, cyclic AMP response element binding protein; DMSO, dimethylsulphoxide; Dox, doxycycline; ERK, extracellular signal-regulated kinase; WIN, WIN 55,212-2.