The main RA factors modified by polyphenols are mitogen-activated protein kinase (MAPK), interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), nuclear factor κ light chain enhancer of activated B cells (NF-κB) and c-Jun N-terminal kinases (JNK). Here, MAPK8 is linked to rheumatoid arthritis.