CHEK1 and glioblastoma: Therefore, we tested a new strategy to overcome the high radio- and chemotherapy resistance of glioblastoma cells using the checkpoint kinase 1 (Chk1) inhibitor SAR-020106 (SAR) and the epigenetic modulator and cytotoxic agent decitabine (5-aza-2’-deoxycytidine, 5-aza-dC).