PTGS2 and rheumatoid arthritis: In the subsequent experiments, researchers found that the chloroform/methanol extract (T2), ethyl acetate extract (EA) extract and the triptolide component could suppress the production of PGE2 via blocking the COX-2 upregulation in RASF of RA in a dose-dependent pattern (p < 0.05) in joint tissues of CIA mice (Tao et al., 1998; Lin et al., 2007).