TNF and rheumatoid arthritis: To elucidate whether MAPK pathways mediate the enhanced proliferation, invasion, and MMP expression by knockdown of nrf2 in RA-FLS, phosphorylation of ERK and JNK was examined.Neither TNF-α (25 ng/mL) treatment nor nrf2 siRNA changed the phosphorylation level of ERK (Figure 6(a)).