Figure. Concentration-dependent activation of FPR1 by fMLP. Reporter cells were transfected with either the expression plasmid for formyl pep­tide receptor 1 (FPR1) or the mock plasmid and treated with various concentrations of N-formyl­meth­ionyl-leucyl-phenyl­alanine (fMLP). 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 3.5 nM.