It is a potent inhibitor of JAK 1 and JAK 3 which binds to β and γ chains of cytokine receptor, respectively, to which inflammatory mediators such as IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21 attach to initiate synovial inflammation in RA [32, 33]. The gene discussed is IL21; the disease is rheumatoid arthritis.