DLL1 and glioblastoma: Here, we have evaluated the expression of fifteen Notch genes (Notch1–4, Dll1/3/4, Jag1/2, Hes1/2/5/6 and Hey1/2) and seven hypoxia markers (HIF-1α, PGK1, VEGF, CA9, GLUT1, EPO and OPN) in 35 primary human GBM specimens and determined the molecules defining the hypoxia-Notch signaling axis.