- HER2 overexpression and activation, and tamoxifen efficacy in receptor-positive early breast cancer. Singer, C.F., Gschwantler-Kaulich, D., Fink-Retter, A., Pfeiler, G., Walter, I., Hudelist, G., Helmy, S., Spiess, A.C., Lamm, W., Kubista, E. J. Cancer Res. Clin. Oncol. (2009)