ERBB2 and thymoma: Similarly, HER2-based vaccination approaches have been well studied in numerous animal model systems, such as mouse mammary D2F2 cells expressing HER2 [13], mouse colon CT26 cells expressing human erbB-2 (HER2) [14, 15], mouse thymoma EL40 cells expressing HER2 [16] and TUBO cells (rat neu transplantable mouse mammary carcinoma cells from BALB-rat neu transgenic mice) [17].