FIGURE 3.

Bile acid-induced activation of mitogen-activated protein kinases in quiescent HSC. Quiescent HSC were exposed to TLCS (100 μmol/liter) for the time periods indicated. When indicated, CHX (0.5 μmol/liter) was added simultaneously with TLCS. Phosphorylation of Erk1/2, p38^MAPK, and JNK1/2 was analyzed by Western blot using phospho-specific antibodies. Total Erk1/2, p38^MAPK, and JNK1/2 served as loading controls. TLCS induced within 30 min a phosphorylation of Erk1/2 but only a weak JNK signal, and no p38^MAPK phosphorylation became detectable. Coadministration of TLCS/CHX resulted in a substantial JNK1/2 and p38^MAPK phosphorylation, whereas the Erk signal was suppressed. For statistical analysis see supplemental Fig. 4. Representative experiments from a series of six independent experiments are shown.