ERBB2 and breast cancer: Based on the MMTV-Her2 breast cancer mouse model, it was postulated that only a subpopulation of early breast cancer cells with either a Her2+, Skp2high, Tpl2low, phospho-MAPKlow, CDH1low phenotype, or a Her2+, CK8/18+, Wnthigh, phospho-MAPKlow, Twist1high, CDH1low phenotype can disseminate and metastasize.