An isolated polypeptide containing the sequence of SEQ ID NO:1 or a
functional equivalent of SEQ ID NO:1, in which the polypeptide reduces
15-keto prostaglandin but not leukotriene B4. Also disclosed is an
antibody that binds specifically to the polypeptide and a double-stranded
ribonucleic acid for inhibiting expression of the 15-keto
prostaglandin-.DELTA..sup.13-reductase.