Fig. 3. Histone H3 phosphorylation and ERK phosphorylation occur in the same hippocampal neurons. (A) Immunohistochemistry using P.ERK antibody on mouse hippocampal cryosections obtained from mice sacrificed 1 hour after saline, SKF82958, pilocarpine or kainic acid injection. (B) IHC was performed using anti-P.H3 (NBT/BCIP staining, top), anti-P.ERK (DAB staining, middle) and a mix of these two antibodies (bottom). The DG regions are shown. (C) Quantification of the data in (B). Cell counts were performed under the light microscope. Statistical comparisons were performed with one-way ANOVA followed by Bonferroni's post hoc test. ^***, P<0.001. (D) High magnifications of CA1, CA2 and CA3 regions revealed with both anti-P.H3 and anti-P.ERK antibodies. Scale bars, 300 µM (A); 20 µM (B,D).