The anti-angiogenesis functions of miR-34a were mediated by reducing the production of CD44. Knockdown of CD44 by siRNA inhibits tube-formation and increased CD44 expression could efficiently reverse the effect of anti-angiogenesis of miR-34a in bladder cancer cells A, EMT related factors and VEGF was detected by qPCR. Data are plotted as the mean ± SEM of 3 independent experiments. B, western blotting indicated that transfection of si-CD44, into 5637 and T24 cells resulted in decreased CD44 expression when compared with negative control. Western blotting indicated that transfection of CD44 restored the downregulation of CD44 induced by stable miR-34a overexpression. C and D,the tube formation of endothelial HUVEC cells was suppressed by treatment with the medium preconditioned by CD44-knockdown 5637 and T24 cells, when compared with that of control cells. E and F, increased CD44 expression could efficiently reverse the effect of anti-angiogenesis of miR-34a in bladder cancer cells. *, P < 0.05; **, P < 0.01. G, exchange of EMT-driving transcription factors, LEF1 and Axin-2 in T24/5637-mir-34s.