EGFR and glioblastoma: The EGFR family is a group of RTKs comprising EGFR, human epidermal growth factor receptor-2 (ErbB2/HER2), ErbB3/HER3, and ErbB4, of which EGFR is involved in the RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway, the PI3K/AKT pathway, the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, and the protein kinase C (PKC) pathway, and may play a primary role in the GBM onset, resistance to therapy, and recurrence[56–57] (Fig. 3).