Interestingly, Bax and Noxa can be transcriptionally upregulated by p53, a tumor suppressor that is upregulated in response to IR.40, 41, 42 Alterations of p53 are commonly observed in glioblastoma.43 We found that p53 levels were already elevated in non-irradiated T98G, U373, and WKI cells, suggesting that p53 was mutated in these cell lines (Supplementary Figure S2). This evidence concerns the gene PMAIP1 and glioblastoma.