FIGURE 1. GalN/LPS co-administration leads to prolonged JNK activation before the onset of caspase cleavage.

A, protein was isolated from the livers of C57BL/6 mice that were untreated or treated with LPS or GalN/LPS for the number of hours indicated. Samples were immunoblotted with antibodies against phospho-JNK (P-JNK), total JNK, caspase-3 and -7, PARP, and β-actin. The p54 and p46 JNK bands are labeled, and arrows indicate the caspase-3 and -7 and PARP cleavage products. B, hepatic JNK activity was determined in untreated and LPS- or GalN/LPS-treated livers by an in vitro kinase activity assay employing c-Jun as substrate. JNK activity was assayed by immunoblots for phosphorylated c-Jun (P-c-Jun) as described under “Experimental Procedures.” Stripped membranes were immunoblotted with an anti-total c-Jun antibody to check the equivalency of protein loading. Results are representative of three independent experiments.