Moreover, over-expression of miR-130b promoted drug resistance, proliferation and decreased apoptosis of MCF-7 cells, while suppression of miR-130b enhanced drug cytotoxicity and apoptosis, as well as reduced proliferation of MCF-7/ADR cells in vitro and in vivo. Particularly, miR-130b mediated the activity of phosphoinositide-3 kinase (PI3K)/Akt signaling pathway as well as the chemoresistance and proliferation of breast cancer cell lines, which was partially blocked following knockdown of PTEN. This evidence concerns the gene PTEN and breast cancer.