To further confirm the causal role of ITGB4 in this process, we ectopically expressed ITGB4 in MLN4924-treated breast cancer cells to reach the levels similar to the basal levels prior to MLN4924 treatment (Figs. 5D and S5D) and found that migration and invasion inhibited by MLN4924 were fully rescued (Figs. 5E and S5E) in both MDA-MB-231 and SK-BR3 breast cancer cells. This evidence concerns the gene ITGB4 and breast cancer.