mice were treated three times a week for 3 weeks with intravenous tail vein injections of either vehicle (2.25% Pluronic P123 in PBS) or JS-K (6 μmol/kg in the vehicle).

Human U87 cells (HTB-14), fibroblasts (CRL-1634), and astrocytes (CRL-8621; ATCC) were cultured in Dulbecco’s Minimal Essential Eagle Medium (DMEM; Gibco, USA) supplemented with 10% fetal calf serum (FCS) and penicillin (100U/mL)/streptomycin (100mg/mL) under normoxic conditions (95% air, 5% CO2, and 37°C). The nitric oxide donor JS-K (O2-(2.4-dinitrophenyl) 1-[(4-ethoxycarbonyl) piperazin-1-yl] diazen-1-ium1,2-diolate, CAS 7054 32-12-8) was dissolved in 100% dimethyl sulfoxide (DMSO) in a concentration of 5.2mM. U87 was incubated with JS-K doses of 0–15µM for 4 h. The JS-K solvent control (DMSO≤1%) was adjusted to the highest JS-K concentration used in these experiments. A cesium source emitting γ-radiation was used for radiotherapy (RT; 3×2Gy) with a 24-h interval between each RT dose (Isotopen Diagnostik CIS, Germany).