ABSTRACT
The ErbB family of receptors belong to the type I superfamily of receptor tyrosine kinases. To date, four members of this family have been identified: epidermal growth factor receptor (EGFR) or ErbB1/HER1, ErbB2/Neu/HER2, ErbB3/HER3, and ErbB4/HER4. They are expressed in a variety of tissues including epithelial, mesenchymal, and neural origin, where they exert effects on development, cellular proliferation, and differentiation (1). Structurally, all ErbB receptors share in common an extracellular domain, a membrane-spanning domain, and an intracellular domain that encompasses the tyrosine kinase activity. Through a complex network of downstream cascades, their dysregulation confers poorer prognosis in breast and other solid tumors that overexpress them (2-6).
