the mammalian and mouse "npas2" gene was first sequenced and characterized in 1997 dr. steven mcknight's lab and published by yu-dong zhou et al. the gene’s cdnas encoding mouse and human forms of npas2 were isolated and sequenced. rna blotting assays were used to demonstrate the selective presence of the gene in brain and spinal cord tissues of mice. in situ hybridization indicated that the pattern of npas2 mrna distribution in mouse brain is broad and complex, and is largely non-overlapping with that of npas1.