EGF and glioblastoma: Furthermore, the EGFRvIII mutation is found in a large number of GBM and is the result of deletion of exons 2–7, with truncation of the extracellular portion of the protein and the subsequent inability to bind the ligand EGF, so that the immunotoxin with EGF as carrier ligand will not kill this population of GBM with EGFRvIII mutation [109].