IL21 and rheumatoid arthritis: It has been found that the treatment of TGP can reduce the production of pro-inflammatory cytokines (including serum interleukin [IL]-21, tumor necrosis factor [TNF]-α, and IL-6), and also reduce the phosphorylation of nuclear factor (NF)-κ and STAT3 to improve joint destruction in collagen-induced arthritis (CIA) mice.[20] SIN is a prescription drug approved by China Food and Drug Administration for the treatment of RA.