Determination of mediators for KRS signaling. RAW264.7 cells were treated for 30 min with different concentrations of KRS (A) or for different times at 10 nM KRS (B). The activation of three major MAPKs, ERK, p38 MAPK, and JNK, was determined by detection of their phosphorylation with their phosphospecific antibodies. The total amount of each kinase was determined by Western blotting with specific antibodies. (C) RAW264.7 cells were pretreated with different kinase inhibitors, 50 μM U0126 (MEK inhibitor), 10 μM SB202190 (p38 MAPK inhibitor), 10 μM SB203580 (p38 MAPK inhibitor), and 10 μM LY294002 (phosphatidylinositol 3-kinase inhibitor), and 10 nM KRS was subsequently added. The specific inhibition of ERK and p38 MAPK was confirmed by using the method above. The effects of kinase inhibitors on the KRS-dependent TNF production (D) and MMP-9 production (E) and cell migration (F) were determined. The effects of cholera toxin (CTX) and pertussis toxin (PTX) on the KRS-induced growth suppression (G) and cell migration (H) are shown as previously described.