Pharmacological concentrations of ascorbate radiosensitize glioblastoma multiforme primary cells by increasing oxidative DNA damage and inhibiting G2/M arrest

► Ascorbate (0.5 mM) sensitized glioblastoma multiforme primary cells to 1-Gy radiation. ► Ascorbate (5 mM) plus 6 Gy significantly increased the number of DNA double-strand breaks. ► Ascorbate (5 mM) did not cause G2/M arrest. ► Ascorbate (5 mM) inhibited radiation-induced G2/M arrest in combined treatment.