Fig. 4. Correlation of histone H3 phosphorylation and IEG induction in the hippocampus. Cryosections obtained from mice sacrificed 1 hour after saline, SKF82958, pilocarpine or kainic-acid injection were used for in situ hybridization experiments using c-fos (A), MKP-1 (C, top) and MKP-3 (C, bottom), S³⁵-labeled riboprobes or in situ-immuno hybridization (B), using c-fos DIG-labeled riboprobe (FITC staining) and P.H3 antibody (Cy3 staining). Nuclear localization was assessed by DAPI staining. Scale bars, 300 µM (A,C); 20 µM (B).