PTPRZ1 and schizophrenia: Furthermore, Takahashi et al. (2011) found that the expression of PTPζ is increased in the brains of schizophrenia patients, and also demonstrated that transgenic mice overexpressing PTPζ showed reduced Neuregulin-1 signaling, and abnormal glutamatergic, GABAergic and dopaminergic activity as well as delayed oligodendrocyte development.