Figure 2. The effect of naloxone on the ability of DAMGO to recruit β-arrestin.

Concentration effect curves for DAMGO were determined in the absence or presence of 31.6 µM, 3.16 µM or 10 µM naloxone in U2OS µ-opioid receptor β-arrestin cells in the absence (A) or presence (B) of co-expressed GRK2.