Four classical GBM cell lines (U87-MG, U251-MG, D566-MG and T98G), selected for their varied p53, MGMT status, and hypoxia sensitivity were cultured in three different oxygen tensions (21%, 1% and 0.1% O2), and GLUT1 or VEGFA levels assessed by RT-PCR to confirm hypoxia had indeed resulted in hypoxia-induced gene expression changes (Fig. S1). Here, MGMT is linked to glioblastoma.