Growth of UACC-812 xenografts treated with various anti-HER2 treatments, with or without estrogen deprivation. (A) Treatment in the presence of estrogen supplementation, representing no endocrine therapy. Treatments included: Estrogen alone (E2) or with lapatinib (E2 + L), trastuzumab (E2 + T), or their combination (E2 + L + T). (B) Treatments in the presence of endocrine therapy in the form of estrogen deprivation. Treatments included: Estrogen (E2), estrogen deprivation (ED) alone, or along with lapatinib (ED + L), trastuzumab (ED + T), or their combination (ED + L + T). Results are presented as the mean tumor volume; error bars represent the standard error.