Although the signals and epigenetic alterations that lead to this aberrant proliferation of SF subsets in RA remain under investigation, in this study we uncovered a novel role for Mir221/222 in the mesenchyma, where increased levels of Mir221/222 rendered fibroblasts more proliferative and migratory, even in the absence of an inflammatory trigger. The gene discussed is MIR221; the disease is rheumatoid arthritis.