Figure 1. Response of ACTOne MC5R cell line & parental cell line to [Nle4, D-Phe7] a-MSH. ACTOne MC5R 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 [Nle4, D-Phe7] a-MSH. Ratios of the two readings (F/F0) are plotted in the figure. A. Dose response curve of [Nle4, D-Phe7] a-MSH, in ACTOne MC5R cell line. EC50 = 2.1 nM in the presence of PDE inhibitor, Ro 20-1724. B. Parental cells do not respond to [Nle4, D-Phe7] a-MSH.