Figure 6.

Enhanced reporter signal from association of CXCR7 with β-arrestin-2. 293T cells were transiently transfected with CXCR7-NLuc and β-arrestin 1-CLuc or β-arrestin 2-CLuc, respectively. Cells were cotransfected with GL to normalize for transfection efficiency. Forty-eight hours after transfection, cells were treated with increasing concentrations of CXCL12. Firefly luciferase bioluminescence produced by living cells was quantified 1 hour after adding chemokine (n = 4 per condition), and these values were normalized to GL activity. Bioluminescence data for chemokine-stimulated recruitment of β-arrestin 1 or β-arrestin 2 to CXCR7 are expressed as mean values relative to bioluminescence in unstimulated cells. Error bars, SEM. Data are representative of three independent experiments. *P < .05; **P < .01.