EGFR and cancer: Through the activation of various intracellular signaling pathways such as RAS‐MAPK, PI3K‐Akt, and cyclin‐dependent kinases (CDKs), EGFR overexpression and mutations (Most are deletions in exon 19 or L858R in exon 21) confer a dysregulated and/or constitutive proliferative activity to cancer cells.