Fig. (4) Profiling of receptor/G protein coupling. HEK293 cells transiently expressing various luciferase reporters as indicated: CRE-luc2P (A), NFAT-RE-luc2P (B), SRE-luc2P (C) or SRF-RE-luc2P (D) were induced with carbachol (for exogenously introduced m3 muscarinic receptor) or isoproterenol (for endogenous β₂-adrenergic receptor) for six hours in 96-well format. Firefly luciferase activity was measured using One-Glo assay system.