PTEN and glioblastoma: CRISPR/Cas9 has been increasingly used for genomic silencing, and knock in and knockout for targeted gene mutation to generate more accurate diseased animal models and thereby to discover the real cause for the diseases [94, 96, 97] (Figure 3), such as CRISPR/Cas9-mediated somatic deletion of a single Ptch1 locus or deletion of TP53, Pten and NF1 simultaneously resulted in the development of medulloblastoma and GBM in the mouse brain [98].