ERBB2 and breast cancer: As illustrated in Fig. 5a-c, lapatinib significantly suppressed HCC1954 xenograft growth in vivo, while the combo treatment with lapatinib and lovastatin further decreased the sizes and weights of xenograft tumors formed in athymic nude mice, suggesting a synergistic effect of lovastatin with lapatinib to restrain the in vivo growth of ErbB2-positive breast cancer.