Brain cancer, Drug therapy, Neuroscience, Oncology, hypoxia, Animals, Antineoplastic Combined Chemotherapy Protocols, Brain Neoplasms, Cell Proliferation, DNA Damage, DNA, Neoplasm, Glioblastoma, Humans, Hydrogen-Ion Concentration, Mice, Nude, Neoplastic Stem Cells, Phenylurea Compounds, Sulfonamides, Temozolomide, Xenograft Model Antitumor Assays