MGMT and glioblastoma: On the basis of the MSP assay and bisulphite sequencing some studies have claimed homogeneity in MGMT status within glioblastomas (Grasbon-Frodl et al, 2007), whereas others have reported a degree of intratumoral heterogeneity (Juillerat-Jeanneret et al, 2008; Parkinson et al, 2008).