We found that the expression of miR‐200c was significantly increased in SKBR3‐S and SKBR3 but not in MCF‐7‐S and MCF‐7 (Figure 3D), indicating that upon treatment with trastuzumab, the expression of miR‐200c was up‐regulated only in HER2+, not HER2‐, breast cancer cells and stem cells. Here, ERBB2 is linked to breast cancer.