Figure 7.

Assessment of cross-talk between GPR55 and CB₂R by DMR label-free technology. All stable cell lines were stimulated with increasing concentrations of LPI and the resulting picometer shifts (pm) of reflected light wavelength against time (s) were monitored and are shown for (A) HEK-GPR55 cells and (B) HEK-CB₂R/GPR55 cells. (C) Transformation of optical signatures was made by using the AUC values between the 0 and 3600 s time points. Data were normalized and expressed as % of maximum activation induced by LPI in HEK-GPR55 cells. Data are the mean ± SEM of at least three independent experiments each performed in triplicate. Statistical analysis was performed for LPI-mediated responses in HEK-GPR55 versus HEK-CB₂R/GPR55 cells by two-way anova followed by Bonferroni's post hoc multiple comparison test. **P < 0.01; ***P < 0.001. (D) HEK-GPR55 and HEK-CB₂R/GPR55 cells were seeded as in panel A–C and were then pre-incubated with either 1 μM AM 630 or the vehicle (DMSO) for 1 h. Cells were then stimulated with increasing concentrations of LPI as in panel A–C. Data are analysed as in panel C and are the mean ± SEM of three independent experiments each performed in triplicate. Dashed curves represent data that are taken from Figure 7C and are depicted again to facilitate comparison.