The Epidermal Growth Factor Receptor (EGFR) pathway is a critical signaling cascade that regulates key cellular processes such as proliferation, differentiation, migration, and survival. EGFR is a transmembrane receptor tyrosine kinase that becomes activated upon binding to specific ligands like EGF or TGF-α. The EGFR pathway operates in various tissues throughout the body, influencing how cells respond to external signals. Proteins play a key role in signaling and immune response within this pathway. Ligand binding induces receptor dimerization and autophosphorylation, triggering downstream signaling through major pathways including RAS/RAF/MEK/ERK, PI3K/AKT, and JAK/STAT. EGFR signaling influences cell growth and survival, and mutations in the EGFR gene can lead to abnormal cell proliferation and tumor formation, contributing to the development of cancer.

Our interactive EGFR pathway gives you an overview of these molecular interactions, highlighting key nodes, feedback loops, and drug targets.

Get your interactive EGFR pathway

EGFR signaling

The EGFR signaling pathway is a sophisticated network that begins when specific ligands bind to the EGFR protein on the cell surface. EGFR is a protein that, upon activation, interacts with other proteins to transmit signals inside the cell. This interaction causes the receptor to pair up, or dimerize, and become activated. Once activated, EGFR initiates a series of downstream signaling events through pathways such as  MAPK/ERKand PI3K/AKT. These pathways are responsible for promoting cell growth, division, and survival under normal conditions. However, mutations in genes like EGFR can lead to abnormal signaling, causing oncogenesis by enabling unchecked cell proliferation and the formation of tumors.

EGFR in glioblastoma

EGFRvIII (Epidermal Growth Factor Receptor variant III) is a mutant form of the EGFR gene, resulting in a variant protein commonly found in glioblastoma, the most aggressive form of primary brain tumor. This variant arises from an in-frame deletion of exons 2–7, resulting in a truncated extracellular domain that renders the receptor protein constitutively active, independent of ligand binding. Approximately 25–30% of glioblastomas express EGFRvIII, particularly in tumors with EGFR amplification.

Unlike wild-type EGFR, EGFRvIII drives persistent downstream signaling, especially through the PI3K/AKT and STAT3 pathways, promoting tumor cell proliferation, survival, and resistance to apoptosis. Despite its oncogenic potential, the prognostic significance of EGFRvIII remains controversial, with some studies showing no clear correlation with patient survival.

EGFRvIII-positive glioblastomas often exhibit distinct molecular profiles, including lower frequencies of CDK4 and MDM2 amplifications, suggesting unique oncogenic dependencies.