Human epidermal growth factor receptor 2 (HER2), also known as ErbB2 and Neu, is a cell surface receptor and member of the EGF family of receptor tyrosine kinases that is encoded by ERBB2 in humans.1 It is a transmembrane receptor composed of a C-terminal intracellular tyrosine kinase domain, a transmembrane lipophilic segment, and an N-terminal extracellular domain, that is expressed at low levels in various epithelial tissues, as well as breast, lung, kidney, ovary, placenta, and the gastrointestinal tract.2 Unlike other EGF receptors, HER2 does not bind ligands or undergo a conformational change in its extracellular domain for activation. HER2 is activated upon heterodimerization with HER3 or HER4, which stabilizes ligand binding to HER3 and HER4, or homodimerization and enhances kinase-mediated activation of the MAPK and PI3K cellular signaling pathways.1,2 Truncated forms of HER2 with constitutive oncogenic activity can be generated by proteolytic cleavage of the extracellular domain.2 ERBB2 is overexpressed in 12 to 15% of breast cancer tumors and is associated with accelerated growth rate, increased rate of recurrence, and poor overall survival.2 Various mutations in ERBB2, with or without gene amplification, have been found in prostate, colon, bladder, breast, lung, and colorectal tumors, as well as metastatic cutaneous squamous small cell carcinomas.3,4 Cayman's HER2/ErbB2 Chimeric Monoclonal Antibody (Clone 4D5-8 (Trastuzumab)) was produced recombinantly from the original humanized 4D5-8 antibody and can be used for ELISA, flow cytometry (FC), and immunohistochemistry (IHC) applications. The 4D5-8 antibody was generated by fusing human IgG1 constant domains to the antigen-binding domain of a mouse anti-HER2/ErbB2 monoclonal antibody.5WARNING This product is not for human or veterinary use.
