A recombinant 130-kDa protein is constructed by linking together human cyclooxygenase (COX) isoform-2 (COX-2) and prostacyclin synthase (PGIS), via a 10-20 amino acid residues of a transmembrane sequence. The engineered protein is expressed in cells, and adopts the functions of COX and PGIS, to continually convert arachidonic acid (AA) into prostaglandin G2 (catalytic step 1), prostaglandin H2 (catalytic step 2) and prostacyclin (PGI2 catalytic step 3).