As tumor cells that undergo EMT have been suggested to acquire properties of normal mammary stem cells [73], and since residual tumor cells surviving HER2/neu (but not Wnt1) downregulation exhibited features of EMT, we wished to evaluate whether HER2/neu or Wnt1 residual tumor cells exhibit gene expression profiles similar to those of mammary stem cells. This evidence concerns the gene ERBB2 and neoplasm.