Human U87 glioma cells were obtained from American Type Culture Collection (ATCC, Manassas, VA) and grown in complete Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10 % fetal calf serum at 37 °C and 5 % CO2. Human GSCs MGG4, MGG8, MGG18, BT74 were isolated as previously described [28 (link),30 (link)], and maintained as spheres in serum-free medium containing 20 ng/mL recombinant human EGF (R&D systems) and 20 ng/mL recombinant human FGF2 (Peprotech). GSCs were passaged by dissociating neurospheres using the Neuro-Cult Chemical Dissociation Kit (StemCell Technologies). Mouse 005 GSCs were provided by Dr. I. Verma (Salk Institute for Biological Studies, La Jolla, CA) [33 (link), 34 (link)]. Human umbilical vein endothelial cells (HUVECs) were purchased from Lonza. Human brain microvascular endothelial cells (HBMECs) were obtained from Dr. Ken Arai (MGH). Axitinib (Pfizer Inc) was provided by Pfizer and dissolved in DMSO as a 25 mM stock solution for in vitro studies. The final concentrations added to cells had less than 0.5 % DMSO, which was nontoxic to cells.