Huang et al. observed up-regulation of a set of genes related to schizophrenia in human U251 glioma cells, including brain-derived neurotrophic factor (BDNF), NTRK2 (neurotrophic receptor kinase 2), and dopamine receptor D3 (DRD3), due to over-expression of HERV-W env. This up-regulation is associated with increased phosphorylation of the cAMP-response element binding protein (CREB) [146]. Here, BDNF is linked to central nervous system cancer.