ESR2 and glioblastoma: Our results showed that: (1) HDACi such as panobinostat and romidepsin have the potential to upregulate ERβ expression, (2) HDACi sensitizes GBM cells to ERβ agonist therapy in in vitro assays, (3) HDACi uniquely regulates expression of the ERβ1 isoform but not ERβ5 isoform, and (4) HDACi and ERβ agonist therapy enhances mice survival in orthotopic models.