Enrichment of miR-29b has been found in luminal breast cancers where it inhibits metastasis by targeting a network of pro-metastatic regulators involved in angiogenesis, collagen remodeling and proteolysis as VEGFA, PDGF, MMP9, indirectly affecting differentiation and epithelial plasticity, with loss of miR-29b increasing metastasis and promoting a mesenchymal phenotype. This evidence concerns the gene MMP9 and breast carcinoma.