Figure. Concentration-dependent activation of PTGIR by beraprost. Reporter cells were transfected with either the expression plasmid for prosta­gland­in I2 receptor (PTGIR) or the mock plasmid and treated with various concentrations of beraprost. 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 130 nM.