Activation of EP4 receptor signaling contributes to the PGE2-mediated cardiac hypertrophy, since EP4 specific antagonist (L-161982 or ONO-AE3-208) significantly blocked the hypertrophic actions of PGE2, including the protein synthesis, mRNA expression of ANP and BNP in neonatal cardiac cells [66, 68]. This evidence concerns the gene PTGER4 and cardiac hypertrophy.