There has been growing evidence that DISC-1 (Disrupted-in-Schizophrenia) may be a candidate gene for psychiatric illnesses. We reported the existence of DISC-1 protein in the brain and its protein interaction with molecules which are important in neurodevelopment (Ozeki et al, Kamiya et al, SFN 2001). We have analyzed DISC-1 protein expression in more detail. Its expression is more remarkable in developing brains than adult brains. In adults, DISC-1 displays a specified expression in olfactory bulb. In cellular models, DISC-1 protein expression is induced in PC12 cells upon its differentiation. We have examined intracellular distribution of DISC-1 by immunofluorescent staining and biochemical subcellular fractionation. DISC-1 displays a unique intracellular distribution, including perinuclear regions, consistent with the localization of a DISC-1 interactor, NUDEL. We have analyzed functions of DISC-1 using cellular models by modulating its expression levels via overexpression or knocking down expression by...