Aspirin irreversibly inhibits PGHS-1, preventing this isozyme from forming PGH2 or any other oxygenated product; in contrast, aspirin treatment of << PGHS-2 >> causes this enzyme to form 15-hydroxy-5c,8c,11c,13t-eicosatetraenoic acid ([[ 15-HETE ]]) instead of PGH2.