Overexpression of miR-183 inhibits migration in T47D cells. Quantification of migration through 8- m pore inserts by miR-183 transfected cells as a percentage of that achieved by control cells. The migratory cell number was significantly less in cells transfected with pre-miR-183 compared to cells transfected with pre-miR-negative control (*p = 0.001). In the more aggressive SKBR-3 and MDA-MB-231 cells the migratory cell number was higher overall but there was no difference in migratory number between cells transfected with pre-miR-183 and negative controls. Experiments were performed in triplicate.