Interestingly, our proteomic data showed that the chronic treatment with haloperidol induces upregulation of GAD2 in the striatum, an enzyme that regulates GABA (γ-aminobutyric acid) synthesis and whose mRNA and protein expression, along with GAD67, has been consistently shown to be reduced in several brain regions of patients suffering from schizophrenia and related disorders [50–59]. This evidence concerns the gene GAD1 and schizophrenia.