Toi et al. BMC Cancer 2010, 10:56 http://www.biomedcentral.com/1471-2407/10/56 differentiation factor and epidermal growth factor signaling by combinatorial receptor interactions. The EMBOJ 1996, 15:2452-67. 21. Sáez R, Molina MA, Ramsey EE, Rojo F, Keenan EJ, Albanell J, Lluch A, García-Conde J, Baselga J, Clinton GM: p95HER-2 predicts worse outcome in patients with HER-2-positive breast cancer. Clin Cancer Res 2006, 12:424-31. 22. Slamon DJ: The FUTURE of ErbB-1 and ErbB-2 pathway inhibition in breast cancer: targeting multiple receptors. The oncologist 2004, 9(Suppl 3):1-3. 23. Yarden Y, Sliwkowski MX: Untangling the ErbB signalling network. Nat Rev 2001, 2:127-37. 24. Nahta R, Yuan LX, Zhang B, Kobayashi R, Esteva FJ: Insulin-like growth factor-I receptor/human epidermal growth factor receptor 2 heterodimerization contributes to trastuzumab resistance of breast cancer cells. Cancer Res 2005, 65:11118-28. 25. Pandolfi PP: Breast cancer–loss of PTEN predicts resistance to treatment. N Engl J Med 2004, 351:2337-8. Pre-publication history The pre-publication history for this paper can be accessed here:http://www. biomedcentral.com/1471-2407/10/56/prepub doi:10.1186/1471-2407-10-56 Cite this article as: Toi et al.: Differential survival following trastuzumab treatment based on quantitative HER2 expression and HER2 homodimers in a clinic-based cohort of patients with metastatic breast cancer. BMC Cancer 2010 10:56. Page 10 of 10 Submit your next manuscript to BioMed Central and take full advantage of: • Convenient online submission • Thorough peer review • No space constraints or color ﬁgure charges • Immediate publication on acceptance • Inclusion in PubMed, CAS, Scopus and Google Scholar • Research which is freely available for redistribution Submit your manuscript at www.biomedcentral.com/submit