Researchers examine the local communication between endothelial cells and tumors cells and its effects on endothelial cell orientation. The approach uses co-cultured human umbilical vein endothelial cells and breast epithelial tumor cell lines to simulate the tumor-endothelial interaction. The group found the clockwise chirality of the hUVECs was less affected by local hormone signaling and more so by direct physical contact with tumor cells. Specific proteins on the tumor cell binding to others on endothelial cells appeared to play a role in changing the clockwise chirality of hUVECs.