ERVW-1 and schizophrenia: As VPA showed a significant influence on HERV-W and ERV9 transcription but not on HERV-K(HML-2) in cell culture models, we further investigated the transcription of ERV9, HERV-W, and HERV-K(HML-2) in postmortem brain samples of patients with schizophrenia and bipolar disorders with regard to their antipsychotic medication (Figure 3).