PTGS2 and cancer: Associated with the increase in COX-2, there is adecreased expression of 15-hydroxyprostaglandin dehydrogenase (15-PGDH), anenzyme involved in the inactivation of PGE2, in cancer compared to normal tissues [174], as well asupregulation of cytosolic PLA2 (cPLA2), which increases the supply of arachidonic acid substratefor COX-2 [175–177].