PTEN and breast cancer: For instance, miR‐130b regulates drug resistance as well as the proliferation of breast cancer cells by targeting PTEN10; miR‐21 mediates gemcitabine resistance and epithelial to mesenchymal transition through PTEN/Akt pathway.11 The miR‐106b in colorectal cancer plays a role in the regulation of radio‐resistance through the PTEN/PI3K/Akt axis.12 However, the effect of microRNA‐221 on adriamycin resistance through the PTEN/Akt/mTOR axis has not been reported.