Figure 4. IL-10 selectively suppresses JNK activity.
C2C12 myoblasts were pre-treated with IL-10 (10 ng/ml) for 1 h prior to addition of TNFα (1 ng/ml) for another 10 or 30 min. Phosphorylation of ERK1/2 and JNK was detected by probing membranes with P-ERK1/2 or P-JNK specific antibodies. Densitometric summaries were expressed as ratios of P-ERK to ERK (A, B) or as ratios of P-JNK to JNK (C, D). A, Representative western blot and B, densitometric summary of four independent experiments showed that TNFα induced a significant increase in ERK1/2 phosphorylation at 10 min and to lesser extent following 30 min of treatment. This increase in ERK1/2 phosphorylation was not inhibited by IL-10 at any time. C, Representative western blot and D, densitometric summary of four independent experiments demonstrate that TNFα induced a 5-fold increase in JNK phosphorylation at 10 min which returned to basal levels at 30 min. Although IL-10 did not inhibit the ability of TNFα to induce ERK1/2 phosphorylation, IL-10 completely blocked TNFα-induced JNK phosphorylation. * P < 0.05; **P < 0.01