Figure 1. Response of ACTOne SCTR cell line & parental cell line to human secretin. ACTOne SCTR 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 30 min after the addition of secretin. Ratios of the two readings (F/F0) are plotted in the figure. A. Dose response curve of secretin in ACTOne SCTR cell line. EC50 = 1.04 pM in the presence of PDE inhibitor Ro20-1724, and EC50 = 3.17 pM in the absence of Ro20-1724 (data not shown). B. Parental cells do not respond to secretin.