MAPK8 and rheumatoid arthritis: In human RA synovial fibroblasts (RASFs), EGCG dosages of 125, 250, and 500 nM for 24 h inhibited the synthesis of MAPK, MMP-1, MMP-3, p-extracellular regulated kinases (ERK)1/2, p-JNK, p-p38, and AP-1 (RASFs) [50].