As RASFs and synovial macrophages are prominent cell types present in the terminal layer of the hyperplastic synovial tissue which secrete inflammatory cytokines and matrix-degrading enzymes [18, 19], elucidation of the role of ESE-1 in COX-2 regulation is important to gain better understanding of the molecular events that occur in RA synovial tissues. The gene discussed is PTGS2; the disease is rheumatoid arthritis.