To evaluate whether UCP-2 expression was modulated by trastuzumab treatment and whether such change was downstream of HER2 signaling pathway, we first examined HER2 phosphorylation level and UCP-2 expression in tissue samples from HER2-positive breast cancer patients before and after receiving trastuzumab in a neoadjuvant therapy setting by immunohistochemistry (IHC). This evidence concerns the gene UCP2 and breast carcinoma.