MAPK3 and rheumatoid arthritis: Western blotting and RT-PCR indicated that LPA pretreatment in FLS-RA evidently promoted the expression of K-ras, c-Raf, P-p38, and P-ERK1/2, while pretreatment with berberine reversed the above condition (Figures 5(c), 5(d), and 5(j)).