ROBO4 and neoplasm: Among the Slit receptors, Robo4 is expressed almost exclusively in proliferatingendothelium and tumor endothelium [45,66]; however, a recent study has also demonstrated Robo1 expression inhuman lymphatic endothelial cells and its interaction with Slit2 [56]; therefore, by Western blot analysis, we compared the levels of Robo4and Robo1 in primary L-LECs, primary dermal HMVECs, and 293/VEGFR-3, humanembryonic kidney cells manipulated to express VEGFR-3 (as a non-endothelialcontrol).