In contrast to a previous report showing the anti-inflammatory effect of a selective EP4 receptor agonist on acute EAM17, daily treatment with CJ-42794, a selective EP4 antagonist, from day 14 to day 21, significantly exacerbated myocardial inflammation on day 21 compared to vehicle alone (inflamed area: 7.2 ± 1.4% vs. 2.0 ± 0.8%, P = 0.0202; macroscopic score: 2.4 ± 0.2 vs. 1.6 ± 0.2, P = 0.0067; respectively) (Fig. 1A,B). This evidence concerns the gene PTGER4 and inflammatory response.