Various studies have demonstrated increased expression of distinct components of Notch signaling pathway (such as Notch1, Notch2, Dll1, Dll4 and Jag1) and Notch target genes (Hey1, Hey2, Hes1) in glioma cell lines or primary human glioma samples including GBM [197,198,199]. This evidence concerns the gene DLL1 and glioma.