Figure. Concentration-dependent activation of SCTR by secre­tin. Reporter cells were transfected with either the expression plasmid for secre­tin receptor (SCTR) or the mock plasmid and treated with various concentrations of secre­tin. Data points shown are the mean ± SEM of an experiment performed in triplicate, and the curve is a fit to Hill equation with an EC50 of 7.6 nM.