Figure 1. Response of ACTOne CB2 cell line & parental cell line to CP-55940. ACTOne CB2 cells and parental cells (AG-10200-200) were plated overnight in 20 ml culture medium on a BD Biocoat 384 well plate. The next day, cells were dye-loaded with 20 ml/well of 1X Dye-loading solution (ACTOne Membrane Potential Assay Kit). After 2 hours of incubation at room temperature, two readings were obtained prior to and 50 min after the addition of CP-55940. Ratios of the two readings (F/F0) are plotted in the figure. A. Dose response curve of CP-55940 in ACTOne CB2 cell line. EC50 = 16.7 nM in the presence of 25 mM of PDE inhibitor Ro20-1724 and 250 nM of adenosine A2b receptor agonist NECA. B. Parental cells do not respond to CP-55940.