Mkp-1 deficiency enhances Pfkfb3 expression in Escherichia coli–infected mice. WT and Mkp-1 KO mice on a C57/129 background were infected with E. coli (O55:B5) i.v. at a dose of 2.5 × 107 CFU/g b.w. or injected with PBS (controls). Mice were euthanized after 24 h and total RNA was isolated from the livers using Trizol for RNA-seq analyses. The livers were homogenized to extract soluble protein for Western blot analysis. A, heatmap of the mRNA levels of glycolytic enzymes. The copy numbers of RNA transcripts for each gene were normalized to the average number in WT controls to calculate fold change. When the transcript number is 0 for a given gene in a specific animal, we gave an arbitrary number that is lower than the lowest value in that group. These values were log2-transformed to generate the heatmap. Each column represents a distinct animal. ∗p < 0.05, comparing E. coli–infected Mkp-1 KO and E. coli–infected WT mice (t test, n = 4). B, Pfkfb3 mRNA levels in the livers of PBS-treated or E. coli–infected mice determined by RNA-seq. Data are shown as means ± S.E (n = 4 mice in each group). ∗p < 0.05, compared to PBS-treated mice of the same genotype; #, p < 0.05, compared to WT mice of the same treatment (t test, n = 4). C, levels of total and phosphorylated PFKFB3 as well as total and phosphorylated p38 MAPK in the livers of control and E. coli–infected mice. Total and phosphorylated PFKFB3 and p38 MAPK were detected by Western blotting using an antibody against total PFKFB3, Ser461-phosphorylated PFKFB3 (p-PFKFB3), total p38 MAPK, and Thr180/Tyr182-phosphorylated p38 MAPK. Comparable protein loading was verified by Western blotting with β-ACTIN antibody (Lower panel). D, side-by-side comparison of total PFKFB3, Thr180/Tyr182-phosphorylated p38 MAPK, and total p38 MAPK levels in liver samples of large groups of E. coli–infected WT and Mkp-1 KO mice. Each lane was from a distinct animal. Representative Western blotting results are shown. MAPK, mitogen-activated protein kinase; MKP, MAPK phosphatase; PFKFB, phosphofructo-2-kinase/fructose-2,6-biphosphatase.