For example, NOTCH pathway ligands (DLL1, DLL3), receptors (NOTCH1, NOTCH2) and target genes (HES1, HES5) were upregulated in gliomas compared with non-tumor brain tissues.101 NOTCH1 and NOTCH2 knockdown was shown to sensitize CD133+ glioma stem cells to radiation. This evidence concerns the gene DLL1 and central nervous system cancer.