Figure 4.
cAMP inhibits TNF-α-induced JNK activation, but not p38 activation, in L929 cells. Phosphorylation and expression of JNK and p38 in L929 cells were analyzed by immunoblotting after the following treatment. A, L929 cells were pretreated with forskolin (10 μM) for various times as indicated, followed by stimulation with or without 10 ng/ml TNF-α for 15 min. B, L929 cells were pretreated with forskolin (10 μM), PGE2 (10 μM), epinephrine (100 μM), or 6-MB-cAMP (100 μM) for 30 min, followed by stimulation with or without 10 ng/ml TNF-α for 15 min. C, L929 cells were pretreated with forskolin (10 μM) for various times as indicated, followed by stimulation with or without 20 J/m2 UV and incubation for 30 min. D, L929 cells were treated with forskolin (10 μM) for various times as indicated or treated with 10 ng/ml TNF-α for 15 min.