TGF-β promotes cell invasion/migration and the EMT. (a and b) TGF-β knockdown reduces the invasive ability of U2OS and MG-63 cells. TGF-β knockdown decreased the invasive ability of U2OS and MG-63 cells (lower panel) (*P < 0.05). Magnification, × 200. (c and d) The rate of U2OS and MG-63 cell migration. Right panels, quantitative data. *P < 0.05 vs. the si-control group. (e and f) E-cadherin, vimentin, α-SMA, and MMP-2 protein expression levels in MG-63 and U2OS cells with or without si-TGF-β treatment. GAPDH was used as a loading control. Results are expressed as means ± SD of three independent experiments; *P < 0.05 vs. the si-control group.