SOX2 and glioblastoma: By screening the Affymetrix DNA chip-based GeneExpress® database for genes overexpressed in GBM (Weigle et al, 2005), we identified the chip element 33109_f_at representing SOX2. The transcription factor SOX2 was found to be overexpressed in the majority of GBM samples and other brain tumours, whereas expression in normal brain and other non-malignant tissues was almost negligible (data not shown).