Figure 5: Pleiotropic effects of the intracellular and nuclear EGFR signalling cascade after ligand binding. The binding of different ligands triggers a conformation change and autophosphorylation of EGFR. This is followed by consecutive activation of the intracellular tyrosine kinase and various intracellular signalling pathways, and culminates in tumour-cell proliferation, survival, and metastasis. Inhibition of this ligand binding or receptor phosphorylation is a new therapeutic approach in HNSCC.