PTGES3 and infection: Also, the protein levels of COX‐1, cPGES, and FLAP, which are key enzymes in the biosynthesis of pro‐inflammatory PG and LT (Radmark et al., 2015; Smith et al., 2011), were decreased in old PM, along with considerably lower PGE2 and LTB4 formation upon infection with pathogenic E. coli.