PTGS2 and rheumatoid arthritis: The ubiquitin proteasome system (UPS) controls NF-κB activity by regulating the degradation of the inhibitory protein IκB, which results in the expression of many pivotal cytokine and chemokine mediators that contribute to the inflammation response in RA, including TNF-α, IL-6, IL-8, inducible nitric oxidase synthase, and cyclooxygenase-2 (COX-2) [7].