Editing Angiogenesis (section)

====Angiopoietins====
The [[angiopoietins]], Ang1 and Ang2, are required for the formation of mature blood vessels, as demonstrated by mouse [[Gene knockout|knock out]] studies.<ref name="Thurston2003">{{cite journal | vauthors = Thurston G | title = Role of Angiopoietins and Tie receptor tyrosine kinases in angiogenesis and lymphangiogenesis | journal = Cell and Tissue Research | volume = 314 | issue = 1 | pages = 61–68 | date = October 2003 | pmid = 12915980 | doi = 10.1007/s00441-003-0749-6 | s2cid = 2529783 }}</ref> [[Ang1]] and [[Ang2]] are protein growth factors which act by binding their receptors, [[Tie-1]] and [[Tie-2]]; while this is somewhat controversial, it seems that cell signals are transmitted mostly by [[Tie-2]]; though some papers show physiologic signaling via [[Tie-1]] as well.  These receptors are [[tyrosine kinases]]. Thus, they can initiate [[cell signaling]] when ligand binding causes a dimerization that initiates [[phosphorylation]] on key tyrosines.