For these studies, we used immunohistochemistry and in situ hybridization and focused on areas of relevance to schizophrenia and where DAO is reputed to be abundant or important, namely the dorsolateral prefrontal cortex (DPFC), hippocampus, cerebellum and substantia nigra (Katagiri et al., 1991; Horiike et al., 1994; Schell et al., 1995; Brannan et al., 1996; Moses et al., 1996; Wang & Zhu, 2003; Kapoor et al., 2006; Wu et al., 2006; Kawazoe et al., 2007). Here, DAO is linked to schizophrenia.