RBP4-induced expression of MHCII and costimulatory molecules and secretion of proinflammatory cytokines are dependent on Erk, JNK, p38, and NF-κB signaling pathways. A: BMDMs from WT mice were stimulated with RBP4 for 15 or 30 min, and phosphorylation of JNK, p38, and Erk and IκBα disappearance were evaluated by Western blot. Data are representative of 3 independent experiments. B: BMDMs were stimulated with RBP4 (50 μg/mL for 24 h) in the presence or absence of p38, Erk, JNK, and NF-κB inhibitors (inh). MHCII and costimulatory molecule (CD80, CD86, and CD40) levels. C: TNF, IL-6, and IL-12 levels. n = 4 mice/group. Values are means ± SEM. *P < 0.05 vs. all other groups. #P < 0.05 vs. nonstimulated control group. MFI, median fluorescence intensity; t-ERK, total ERK.