EGFR and glioblastoma: In particular, hypoxia inducible factor 1-alpha (HIF-1α) levels are elevated in glioblastoma [19], with frequent gene alterations, such as epidermal growth factor receptor (EGFR) amplification, loss of phosphatase and tensin homolog (PTEN) and loss of p53, known to play a role in the upregulation of the protein [20, 21].