Figure 1. The effect of co-expression of GRK2 and subsequent β-funaltrexamine treatment on β-arrestin recruitment in U2OS µ-opioid receptor β-arrestin cells.

Concentration-effect curves for DAMGO, morphine, Pfizer standard 1, endomorphin-1, endomorphin-2 and oxycodone were performed in U2OS µ-opioid receptor β-arrestin cells which had been transduced with either GFP or GRK2. Cells transduced with GRK2 were also treated with either 1 nM or 10 nM β-funaltrexamine before concentration-effect curves were determined. Experiments were performed as described in the experimental section and data are representative of four independent experiments.