ERBB2 and breast cancer: Since the MMTV-erbb2/MMTV-cre/Rosa26LoxP or MMTV-PyVT/MMTV-cre/Rosa26LoxP exhibits both blue histochemical staining of the ductal tree and the breast cancer grossly and microscopically when the MMTV promoter is stimulated, it would be anticipated that the injected tail vein-derived iPSC clones from either tritransgenic would do the same and this is exactly what was observed.