EGFR and glioblastoma: EGFR is ubiquitously expressed in the epithelial layers of the lung, gut, and skin, and is related to several cancers that show overexpression and mutations in EGFR, such as non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma (HNSCC), melanoma, breast and ovarian cancers, and glioblastoma (GBM) [44,45,46,47,48].