To further explore the NF1-MAPK-FOSL1 axis in MES GBM, we used a combination of the RCAS-Tva system with the CRISPR/Cas9 technology, recently developed in our laboratory (Oldrini et al., 2018), to induce Nf1 loss or Kras mutation. This evidence concerns the gene NF1 and Meckel syndrome, type 1.