MAPK3 and rheumatoid arthritis: To delineate the signaling mechanisms involved, c-Jun N-terminal protein kinase (JNK), p38 mitogen activated protein kinase (MAPK), p44/42 MAPK (Erk1/2), Rho-family-alpha serine/threonine-protein kinase (Akt), paxillin, and focal adhesion kinase (FAK) were investigated in HFLS-RA cells incubated with Mφ-SN.