Work on angiogenesis inhibitors such as angiostatin has generated a lot of newspaper print, but rather less understanding about just how these molecules work. Now, Troyanovsky et al. report on their discovery of angiomotin, an angiostatin-binding protein that appears to be a target for angiostatin action (page 1247). Angiomotin is not a transmembrane protein, however, and does not appear to act as a traditional signal-transducing receptor for angiostatin.
Only cells that contain, or are transfected with, angiomotin show the following responses to angiostatin: the internalization of angiostatin, an increase in FAK kinase activity, a reduction of both background and growth-factor induced migration rates, and an inhibition of tubulogenesis. As discussed in a comment by Zetter (page F35), angiomotin's localization at the leading edge of migrating cells suggests that it is normally involved in migration, and that the binding of...
