PTGS2 and viral infectious disease: COX exists in two isoforms: COX-1, which is expressed constitutively under normal conditions in most tissues, mediates regulating normal physiological responses, and controls renal homeostasis, and the inducible COX-2, is not detectable in most normal tissues or resting cells, but its expression can be induced rapidly by a variety of stimuli including cytokines, bacterial or viral infections, and other mediators to produce PGs during inflammation [120].