Abdominal adipose tissue inhibits antitumor effect of trastuzumab in vivo. (A) Tumor growth in BT-474 xenograft mice treated with trastuzumab or rituximab in the presence or absence of lipoma. Median ± standard error of the mean data are shown. (B) Normalization of the tumor volumes shown in (A) with the tumor volumes of mice treated with rituximab. (C) Photos of the tumors in contact with the lipomas taken from mice treated with either trastuzumab (left) or rituximab (right). L, Lipoma; ns, Not significant; T, Tumor. **P < 0.01.