ERBB2 and breast carcinoma: Mice knocked out for IL-15 and transgenic for HER2/neu oncogene (IL15KO/NeuT mice) developed mammary carcinomas with a median latency of 16 weeks, significantly shorter than the median latency of 20 weeks displayed by HER2/neu transgenic mice with wild-type IL-15 (NeuT mice) (Fig. 1a).