To examine if sensing of PGE2 produced during inflammation of the intestines was mediated through EP4 on T cells, we injected either EP4fl/fl (virtual WT) and CD4CrexEP4fl/fl (EP4ΔCD4) Teff cells into Rag1−/− recipient animals and evaluated colitis development and T cell phenotype as previously described. This evidence concerns the gene PTGER4 and colitis.