PTGS2 and arthritic joint disease: TNF-α induces inflammation by activating NF-kB and AP-1, two key inflammatory mediators that activate the transcription of an array of inflammatory genes including cyclooxygenase-2 (COX-2) [6, 7], a target of a class of anti-arthritis medications, COXIBs such as celecoxib, etoricoxib and rofecoxib.