FIG. 4.

Induction of C/EBPβ and -δ as measured by Northern blot, Western blot, and EMSA analyses. (A and B) STAT3 conditional-mutant (open bars) and control (solid bars) mice were treated for the indicated times as described in the legend to Fig. 2 with either LPS (A) or recombinant IL-6 (B) and analyzed by Northern blotting. The data are shown as mean values + standard errors of five (A) or three (B) mice per group. The values were normalized and plotted as described in the legend to Fig. 2. The symbols indicate statistically significant differences between the two groups of mice at each time point: #, P < 0.03; ∗, P < 0.01; ‡, P < 0.0001. (C) Western blot analysis of C/EBPβ and C/EBPδ. Mice were treated with LPS as described above for 4.5 or 9 h, and nuclear extracts were analyzed by Western blotting with specific antisera. The different polypeptides detected are indicated. −, negative; +, positive. (D) EMSA analysis of C/EBP binding activities. Nuclear extracts from mice either untreated or treated with LPS for 4.5 h were used in an EMSA with a double-stranded oligonucleotide carrying a C/EBP binding site. Where indicated, antisera against different C/EBP proteins were preincubated with the extracts.