Claudin15 up‐regulation leads to decreased MDA‐MB‐231 breast cancer cell invasion, migration and VM formation in vitro. A, 3D culture in both MDA‐MB‐231 and MCF‐7 cells up‐regulated or down‐regulated for Claudin15 expression on the 3D Matrigel medium (n = 3). B, Wound healing assays of MDA‐MB‐231 and MCF‐7 cells. C, Quantitative analysis of wound healing of MCF‐7 and MCF‐7‐shClaudin15 cells (n = 3). D, Quantitative analysis of wound healing of MDA‐MB‐231 and MDA‐MB‐231‐Claudin15 cells (n = 3). E, Matrigel invasion assays of MDA‐MB‐231‐Claudin15 and MCF‐7‐shClaudin15 cells compared with the control. F, Quantitative analysis of invasion assays (n = 3). E, The Matrigel invasion assay. F, Western blotting of VE‐cadherin, E‐cadherin and Vimentin. The ruler is 100 μm, and the error bar indicates the standard error of mean (SEM). *P < .05, **P < .01, ***P < .001