ERK5 is specifically expressed in the adult neurogenic regions in the mouse brain. Immunostaining of coronal sections of adult mouse brain tissue shows ERK5 protein expression (green) primarily in the SVZ (A, B) and SGZ (C, D) of the hippocampus but is absent in other brain regions such as the cortex (E, F) and striatum (G, H). Hoechst staining (blue) was used to identify all cell nuclei (B, D, F, H). Scale bar, 100 μm.