For example, 35% of proneural glioblastomas have focal amplification of PDGFRA (which encodes platelet-derived growth factor receptor alpha, PDGFRA) whereas 11% have mutations in PDGFRA; 97% of classical glioblastomas have high-level EGFR (encoding epidermal growth factor receptor, EGFR) amplification whereas 55% have mutations in EGFR; and 37% of mesenchymal glioblastomas have a deletion of NF1 (encoding neurofibromin 1, NF1)2. Here, EGFR is linked to glioblastoma.