Figure. Concentration-dependent activation of GHRHR by GHRH. Reporter cells were transfected with the expression plasmid for growth hormone re­leas­ing hormone receptor (GHRHR) and treated with various concentrations of growth hormone–re­leas­ing hormone (GHRH). 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 2.0 nM.