These tumors share high-grade elements such as microvascular proliferation and pseudopalisading necrosis with human GBMs [34], [35] (Fig. 1A,B) These tumors closely mimic the proneural subtype of GBM, in which CDKN2A (encoding for both p16INK4A and p14ARF) and PTEN deletion are observed in up to 56% and 69% proneural human gliomas, respectively [36]. This evidence concerns the gene PTEN and glioblastoma.