Fagiani E Christofori G 2013 Tie-1 and Tie-2 tyrosine kinase receptors are expressed specifically on vascular endothelial cells and on a certain subtype of macrophages implicated in angiogenesis, thus, they have been a major focus of angiogenesis research. Tie-1 and Tie-2 are essential for vascular maturation during developmental, physiological and pathological angiogenesis. Angiopoietin 1-4 (Ang-1-4) have been identified as bona fide ligands of the Tie-2 receptor, while Tie-1 remains an orphan receptor which is able to heterodimerize with Tie-2 and to modulate Tie-2 signal transduction. The most exhaustively studied angiopoietins are Ang-1 and Ang-2. Ang-1 is a critical player in vessel maturation and it mediates migration, adhesion and survival of endothelial cells. Ang-2 disrupts the connections between the endothelium and perivascular cells and promotes cell death and vascular regression. Yet, in conjunction with VEGF, Ang-2 promotes neo-vascularization. Hence, angiopoietins exert crucial roles in the angiogenic switch during tumor progression, and increased expression of Ang-2 relative to Ang-1 in tumors correlates with poor prognosis. Its central role in the regulation of physiological and pathological angiogenesis makes the angiopoietin/Tie signaling pathway a therapeutically attractive target for the treatment of vascular disease and cancer. https://sonar.ch/global/documents/53325 eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.canlet.2012.08.018 info:eu-repo/semantics/altIdentifier/pmid/22922303 Cancer letters. - 2013 Angiopoietins Humans Neoplasms Neovascularization, Pathologic Receptor, TIE-1 Receptor, TIE-2 Signal Transduction Angiopoietins in angiogenesis. http://purl.org/coar/resource_type/c_6501