miR-29b knockdown increases the level of expression of its target genes and miR-29b suppresses metastasis by repressing four microenvironmental targets. (a) Relative expression of miR-29b targets in Zip29-knockdown cells by qPCR (n = 5 independently obtained biological samples, *P < 0.05). (b) The 3′UTR reporters of the indicated miR-29b targets were co-transfected with anti-miR-29b or control inhibitor into HEK293T cells. (n =3 independent experiments performed in triplicate, *P <0.05.) (c,d) BALB/c mice were injected i.v. with 4T1 cells ± miR-29b re-expressing ANGPTL4, LOX, MMP9 or VEGF-A, and euthanized at two weeks. Representative fluorescence micrographs of lungs were taken on a dissection microscope (c) and GFP fluorescence intensity was quantified (d). (n =8 independent mice per group, *P < 0.01.) Data are reported as mean±s.e.m. Scale bar, 1 mm.