Introduction

Since its identification more than 15 years ago, the epidermal growth factor receptor (EGFR) has emerged as a significant factor in the development and growth of many types of solid tumours. The advent of a range of molecular techniques has revealed that the EGFR signal transduction network is involved in multiple tumorigenic processes, contributing to cancer-cell proliferation, angiogenesis and metastasis, as well as protection from apoptosis (reviewed in Ref. [ 1 Huang S.M. Harari P.M. Epidermal growth factor receptor inhibition in cancer therapy biology, rationale and preliminary clinical results. Invest. New Drugs. 1999; 17: 259-269 Crossref PubMed Scopus (223) Google Scholar ]). These techniques have also shown that this receptor tyrosine kinase is the growth-factor receptor most frequently overexpressed in a variety of common solid tumours, including squamous-cell carcinoma of the head and neck (SCCHN) and colorectal, renal-cell, ovarian and non-small cell lung cancers [ 2 Salomon D.S. Bradt R. Ciardiello F. Normanno N. Epidermal growth factor-related peptides and their receptors in human malignancies. Critical Rev. Oncol./Hematol. 1995; 19: 183-232 Abstract Full Text PDF PubMed Scopus (2407) Google Scholar ].