Sensitivity to temozolomide in vitro was consistent with methylguanine methyltransferase (MGMT) and DNA mismatch repair (MMR) status; MGMT+ MMR+ D384Med cells (temozolomide GI50=220 μM), representative of most primary medulloblastomas, were sensitised fourfold by AG-014699; MGMT− MMR+ D425Med cells were hypersensitive (GI50=9 μM) and not sensitised by AG-014699, whereas MGMT+ MMR− temozolomide-resistant D283Med cells (GI50=807 μM) were sensitised 20-fold. This evidence concerns the gene MRC1 and medulloblastoma.