A mammalian odorant receptor, RTP1S, and Ric8b, each contained in a mammalian expression vector such as pCI, are transfected into HEK293T or the HEK293T-derived Hana3A cells along with a luciferase reporter gene construct driven by a cyclic AMP responsive element (CRE) promoter and Renilla luciferase construct drive by an SV40 promoter. Typically one day after transfection, cells are stimulated with potential odorants. Activation of the odorant receptor leads to accumulation of cyclic AMP (cAMP) which turns on the expression of the luciferase reporter gene.