H2AX and glioblastoma: Treating cells with 10μM of 6-MP, which was far lower than its IC50 to GBM cells (Supplementary Fig. 10c), significantly increased TMZ sensitivity as reflected by suppressed cell proliferation (Supplementary Fig. 10d) with prolonged expression of γ-H2AX (Supplementary Fig. 10e) and increased apoptosis (Supplementary Fig. 10f).