Treatment of the glioblastoma cell line U251-MTH1 (MTH1 deficient) and the isogenic U251 cell line (MTH1 proficient) (Supplementary Figure S6) with Temozolomide shows that the cells lacking MTH1 are more sensitive to Temozolomide as assessed by viability assay using resazurin (Figure 7A) with EC50 values 3.6-fold higher for the MTH1 proficient cell line (62±4 μM) compared to the MTH1 deficient cell line (17±10 μM). Here, NUDT1 is linked to glioblastoma.