Strikingly, H&E staining indicated that although lapatinib treatment can completely block MMTV-HER2 tumor cell lung metastasis, MMTV-HER2/MMTV-MED1 tumors can still actively metastasize to lung even in the presence of lapatinib, just like the vehicle-treated MMTV-HER2 control group (Figures 5E and 5F). The gene discussed is ERBB2; the disease is neoplasm.