The floating cells were removed by washing with phosphate-buffered saline, and images of the wounds were obtained using a microscope. RNA isolation and qRT�CPCR Total RNA inhibitor MEK162 was extracted using TRIZOL reagent (Invitrogen). The PRL-3 mRNA level was determined using the SYBR PrimeScript RT�CPCR Kit (Takara) with the following primers: PRL-3 forward, 5��-GGGACTTCTCAGGTCGTGTC-3�� and PRL-3 reverse, 5��-AGCCCCGTACTTCTTCAGGT-3��. The quantitative reverse-transcription polymerase chain reactions (qRT�CPCR) assays for miR-17, miR-19a and miR-21 were performed using the Hairpin-it miRNA qPCR Quantitation Kit (GenePharma, Shanghai, China). All quantitative real-time PCR was performed using a LightCycler 480 (Roche, Basel, Switzerland) according to the operating instructions.

MicroRNA transient transfections All of the miRNA mimics and inhibitors were designed by and purchased from GenePharma. Because the mimics are duplexes, the effective concentration of active miRNA mimic (i.e., the strand loaded into RISC) within the cell was half of the total transfected concentration (100n). The inhibitors are single-stranded, special antisense miRNAs (anti-miRs), and the total transfected concentration is 200n. Transient transfections were performed using Lipofectamine 2000 (Invitrogen), according to the protocol provided with the reagent. Western blotting The cells were lysed with RIPA buffer (Beyotime Biotechnology, Haimen, China), and the extracted proteins were separated using SDS�CPAGE gels and then transferred onto PVDF membranes (Millipore, Bedford, MA, USA) for western blotting.

The following primary antibodies were used: anti-STAT3 (Cell Signaling, Beverly, MA, USA), anti-pSTAT3 (Tyr705) (Cell Signaling), anti-Csk (Cell Signaling), anti-pSrc (Tyr527) (Cell Signaling), anti-pSrc (Tyr416) (Cell Signaling), anti-PTEN (Cell Signaling), and anti-PRL-3 (Abcam, Cambridge, MA, USA). The antibody dilutions were 1:1000 for anti-STAT3, -pSTAT3, -Csk, -pSrc, -PTEN, and -PRL-3 and 1:2000 for anti-GAPDH. Invasive assay Transwell chambers precoated with Matrigel (BD Bioscience, San Jose, CA, USA) were used to perform the invasion Batimastat assay. Cells were cultured in serum-free medium in the upper chambers of a Transwell (Corning, NY, USA) plate (1 �� 105 cells per chamber), which are separated from the lower chambers with permeable 8.0��m polycarbonate membranes; medium containing 10% FBS served as the attractant in the lower chambers. After 12h, the cells were fixed with 75% ethanol and stained with crystal violet. Non-migrating cells on the upper side of the membrane were gently wiped off, and the stained cells on the lower side were observed under a microscope. The number of migrating cells in five fields per chamber were counted and average values were calculated.