Effects of miR-224 mimics transfection on cell proliferation, apoptosis, invasion, and migration of A549 cells. (A) The expression level of miR-224 in miR-224 mimics transfected cells was significantly higher compared with NC transfected cells. qRT-PCR was done to detect the expression of miR-224. U6 RNA was used as an internal control. ***p <0.001. (B) Cell proliferation was measured by MTT assays in A549 cells transfected with miR-224 mimics or negative control. Data represent the mean ± SD of the experiments performed in triplicate. **p <0.01. (C) Apoptosis of A549 cells was detected by flow cytometric analysis after transfection with miR-224 mimics or negative control. (D, E) miR-224 suppressed A549 cell invasion and migration in vitro. The Matrigel invasion and migration assays showed that the number of invaded or migrated cells was significantly lower in the miR-224-transfected group than in the NC-transfected group. **p <0.01. (F) Scratch migration assay confirmed the inhibitory effect of miR-224 on A549 cell migration.