In more than half of GBs, transcription of the DNA repair enzyme O6-methylguanine-DNA-methyltransferase (MGMT) from an unmethylated gene promoter renders tumour cells resistant to temozolomide.7 Acquired resistance to temozolomide can involve defects in the DNA mismatch repair pathway reducing susceptibility to apoptosis.8 Adaptation to conditions of the tumour micromilieu is a selective advantage mediated by cellular sensors. The gene discussed is LIG4; the disease is neoplasm.