Thus, this model provides novel insights into the relation between benign lesions and aggressive tumours as it shows that: (1) RAS/MAPK signalling can induce both heterotopia (non-cancerous benign lesions) and aggressive brain tumours; (2) aggressive tumours have a mesenchymal GBM signature; (3) activation of YAP signalling distinguishes aggressive tumours from heterotopia; and (4) forcing the activation of YAP signalling at earlier stages promotes aggressive tumours at the expenses of heterotopia. This evidence concerns the gene YAP1 and glioblastoma.