NOTCH1 and glioblastoma: Furthermore, we used the CRISPR (clustered regularly interspaced short palindromic repeat)/Cas9 (CRISPR-associated nuclease 9) system to ablate the Notch1 gene in human GBM cells and investigated the effects of Notch1 downregulation on clonogenic growth and angiogenesis of GBM cells and xenografts.