Zhou et al. found that 5-aza-2′-deoxycytidine (5-AzadC) represses the methylation of miR-124a in RA FLS and restores RA FLS proliferation and TNF-α expression [41], suggesting that DNA methylation of a single gene could regulate inflammatory cytokine secretion and RA development. The gene discussed is TNF; the disease is rheumatoid arthritis.