Wei Z, et al. - Researchers investigated how microRNA-221 influence a series of biological behaviors of papillary thyroid carcinoma (PTC) cells in vitro and in vivo and what are the potential mechanisms involved. As per data gained, metastatic PTC tissues show relatively upregulated miR-221. Following variations of epithelial–mesenchymal transition (EMT)-related protein expression, MiR-221 led to enhanced proliferation, migration, and invasion activities of PTC K1 cells. RECK was identified to be a direct target of miR-221 and its expression was inversely associated with miR-221 in PTC samples and further, its reintroduction reverses miR-221-induced PTC invasiveness. In addition, in vivo findings also support miR-221 as a promoter of tumor growth and increase tumor volume and weight. Taken together, biological behaviors of PTC could be effectively regulated targeting miR-221/RECK axis.