BDNF and neuroblastoma: In addition to the above-mentioned observations in neuroblastoma cells, overexpression of HERV-W ENV in human glioma cells was reported to induce expression of SCZ-linked genes encoding brain-derived neurotrophic factor (BDNF) and dopamine receptor D3 (DRD3; Huang et al., 2011), whereas the endogenous retroviral insert hsERVPRODH was found to act as a tissue-specific enhancer for the proline dehydrogenase 1 (PRODH), a candidate gene for SCZ susceptibility (Suntsova et al., 2013).