The majority of FosB/ΔFosB-immunopositive cells in the hippocampus are principal cells.

<p><b>(A)</b> Photomicrographs illustrating double immunofluorescence experiments in the CA1 region against CamKII (green) and FosB/ΔFosB (red) in a representative mouse. The vast majority of FosB/ΔFosB-positive cells were also positive for CamKII. <b>(B)</b> Photomicrographs illustrating double immunofluorescence experiments in the CA1 region against GAD67 (green) and FosB/ΔFosB (red) in a representative mouse. Few (arrows) FosB/ΔFosB-positive cells were also positive for GAD67. Scale bars = 50 μm.