ERBB2 and neoplasm: Research by Husemann et al. [37] using two transgenic mouse models (HER2 transgenic mouse model—BALB-NeuT, and mouse mammary tumour virus-polyoma middle T-antigen transgenic mouse model—MMTV-PyMT) demonstrated that dissemination of tumour cells can occur in pre-invasive stages of tumour progression and that the number and genotype of seeded tumour cells were not associated with tumour size.