The 10q26.3 region is frequently deleted in grade IV brain tumors. Zardo et al. (2002) found that a fragment from that region was aberrantly methylated and deleted in grade IV brain tumors and homozygously methylated in grade II brain tumors. They determined that the fragment maps to the 5-prime end of the EBF3 gene, which the authors called COE3. EBF3 is a COE transcription factor, which regulate neurogenesis and differentiation . RT-PCR analysis detected EBF3 expression in normal adult brain, but expression was repressed in 4 glioma cell lines. Zardo et al. (2002) were able to reactivate EBF3 expression by treating cells with the demethylating agent 5-aza-2-deoxycytidine, suggesting that aberrant methylation causes silencing of EBF3.