AMD3100 inhibits bioluminescence from CXCL12-CXCR4 binding. (A) Cocultures of HeyA8 cells (CXCL12-CG/NG-CXCR4 or CG/NG-CXCR4) were incubated for increasing periods with 1 µM AMD3100, a CXCR4 inhibitor, or CCX771, an inhibitor of CXCL12 binding to CXCR7. Gaussia luciferase bioluminescence was quantified as described in Figure 2, and data were presented as mean values ± SEM (n = 4 per condition). (B) Cocultures of CXCL12-CG/NG-CXCR4 or control CG/NG-CXCR4 cells were incubated for 2 hours with increasing concentrations of AMD3100 or CCX771, respectively, before measuring bioluminescence from Gaussia luciferase (n = 4 per condition). (C) Pairs of HeyA8 cells were incubated for 4 hours before adding increasing concentrations of AMD3100 for an additional 4 hours before quantify bioluminescence (n = 4 per condition). *P < .05. **P < .01.