Source: Active human recombinant N-terminal GST-tagged protein expressed in E. coli ? MW: 55 kDa ? NAD+-dependent 15-PGDH catalyzes the oxidation of PGs to 15-keto metabolites that have greatly reduced biological activity. Three different studies have shown an inverse correlation between 15-PGDH expression and cell proliferation in colon, breast, and thyroid cells.