The importance of immune cells in trastuzumab therapy is supported by studies showing that ADCC contributes mainly to the antitumor effects of trastuzumab in HER2-positive tumors in mice [7] and in breast carcinoma pre-operative clinical studies, in which it was associated with increased tumor infiltration of natural killer (NK) cells [8;9]. The gene discussed is ERBB2; the disease is breast carcinoma.