Prostaglandin receptors and cAMP and PLCβ responses. A) and B) Expression of prostaglandin receptor mRNA in MH1C1 cells (data from three experiments, measured in triplicate) and hepatocytes (data from one experiment measured in triplicate). Quantitative RT-PCR of EP1, EP2, EP3, EP4 and FP normalized to GADPH. RNA was isolated as described in Materials and Methods. * not detected # low levels-not quantifiable. C) Left: Accumulation of cAMP in MH1C1 cells after stimulation with either PGE2 (100 μM) or isoproterenol (10 μM) in the presence of 0.5 mM IBMX. cAMP was measured after 3 minutes. Right: Accumulation of inositol phosphates in MH1C1 cells after stimulation with PGE2 (100 μM) for 30 minutes in the presence of 15 mM LiCl. The data shown are mean ± S.E.M of three independent experiments.