For example, the EGFRvIII (aka EGFRΔvIII) mutant, present in 25–33% of all patients with GBM and representing the most frequent genetic aberration in brain tumors, contains a deletion of exons 2–7 of the EGFR gene, leading to the loss of large parts of the extracellular ligand-binding domain, and hence cannot bind any known ligands [24,31]. Here, EGFR is linked to glioblastoma.