Figure. Concentration-dependent activation of HTR5A by serotonin. Reporter cells were transfected with the expression plasmid for 5-hy­droxy­tryp­ta­mine receptor 5A (HTR5A) and treated with various concentrations of serotonin. 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 85 nM.