MGMT and neoplasm: Celecoxib was selected for further analysis based on its ability to inhibit Wnt signalling17, downregulate MGMT expression (Figs 2e and 3c,d) and induce synergistic toxicity on tumour cells both in combination with temozolomide and several other cytotoxic drugs used as a first-line treatment of different cancers (Fig. 3a and Supplementary Table 1).