[Angiopoietin-2, a new molecular actor involved in vascular tree morphogenesis].

Angiopoietin-2 is a new member of the family of the ligands of Tek (Tie2), a transmembrane receptor with tyrosine kinase activity which is specifically expressed in endothelial cells during angiogenesis. Several lines of evidence indicate that angiopoietin-1 is involved in pericyte recruitment by endothelial cells and in the maintenance of cell-cell and cell matrix association in mature capillaries. Angiopoietin-2 behaves as an antagonist of angiopoietin-1. It is suggested that it looses capillary structure and renders endothelial cells to become responsive to angiogenic stimuli.