Mean EC50 values and amplitude of response for cAMP concentration-response curves in Figure 8A.

EC50 values were determined for each individual experiment, using a sigmoidal concentration-response equation. Compared to wild-type GIPR, the EC50 values for N62,77Q-GIPR when co-expressed with the wild type GLP1R was significantly right shifted, as shown by a one-way ANOVA analysis followed by Dunnett's multiple comparison test. The changes in RFU values for N62,77Q-GIPR or the GLP1R were small and could not be accurately fitted. The amplitude of response was calculated by subtracting the lowest RFU values from the highest for each individual experiment.