Permeability of HBTAEC increased significantly with increasing co-culture duration with highly
metastatic MDA-MB-231 cells (panel A) and was accompanied by morphological changes in endothelial cells
(panels B–D). HBTAEC cultured without tumor cells showed no change in morphology for 120 h (panel B) but
endothelial cell morphology changed significantly when co-cultured with MDA-MB-231 cells for 120 h (panel
C). HBTAEC co-cultured with MCF-7 cells for 120 h showed fewer morphological changes (panel D). Data are
presented as mean ± SEM (n = 3). *Significant difference by two-way ANOVA.