Capsaicin inhibits BCa cell proliferation and migration in vitro. (A,B) Relative cell proliferation of 5637 and T24 cells treated by CAP at distinct concentrations (0, 50, 100, 150, 200 and 300 µM) for 48 h were measured by MTT assay, to determinate the appropriate concentrations of CAP treatment on 5637 and T24 cells. ** p < 0.01, *** p < 0.001; (C) Transwell migration assay for CAP treated 5637 (a–c) and T24 cells (d–f) at 0, 150 and 300 µM for 48 h. The scale bar for (a–f) is 50 μm; (D) Statistical analysis of transwell migration assay, showed significantly reduced migrated cell number of 5637 and T24 cells after CAP treatment at 150 and 300 µM. ** p < 0.01, *** p < 0.001; (E) Western blot analysis for proteins involved in EMT regulation, revealing that E-cadherin and β-catenin were strongly increased, in contrast, N-cadherin was strongly decreased after CAP treatment, whereas Vimentin was only slightly altered. GAPDH was used as a loading control. Cell types, concentrations of CAP and protein masses were indicated. All data shown were mean ± SD of triplicate measurements and repeated at least three independent experiments with similar results.