FIG. 5.

p38 MAPK is necessary for PGC-1α expression and differentially regulates the phosphorylation of CREB and ATF-2 in IBAT. As detailed in Materials and Methods, mice pretreated with the p38 MAPK inhibitor SB (+SB) or vehicle (−SB) were placed at 4°C for the time indicated. IBAT was harvested from individual mice to analyze the following factors by Northern or Western blotting. (A) PGC-1α mRNA and 18S RNA (same as in Fig. 2B). (B) PGC-1α protein. (C) Phosphorylated CREB (CREB-P) and total CREB (CREB-T). (D) Phosphorylated ATF-2 (ATF-2-P) and total ATF-2 (ATF-2-T). The results represent one of four independent experiments.