Overexpression of miR-9 enhances invasion in normal mouse bone marrow-derived mast cells. (A) Normal mBMMCs transduced with pre-miR-9-3 lentivirus or empty vector control were sorted to greater than 95% purity based on GFP expression. MiR-9 levels were assessed by real-time PCR (*p < 0.05). Three independent experiments were performed and all reactions were performed in triplicate. (B) mBMMCs transduced with either empty vector or pre-miR-9-3 lentivirus were transferred onto cell culture inserts coated with Matrigel® for 24 hrs. After incubation, cells remaining on the upper surface of the insert membrane were wiped away using a cotton swab, and cells that had migrated to the lower surface were stained with crystal violet and counted in ten independent 20x hpf for each sample. Three independent experiments were performed and all samples were performed in triplicate wells (*p < 0.05).