ICAM1 and neoplasm: Using the transwell insert pre-coated with confluent human umbilical vein endothelial cells (HUVECs), we added breast tumor cells on top of the endothelial cells in the insert under four different conditions: (i) control siRNA in endothelial cells, (ii) ICAM1 knockdown in endothelial cells alone, (iii) in tumor cells alone, or (iv) in both tumor cells and endothelial cells (Fig. 4a).