Galectin-1 and-9 in angiogenesis: A sweet couple

The growth of new blood vessels out of the pre-existing vas-culature, i.e., angiogenesis, is executed by endothelial cells that normally form the inner lining of blood vessels. During angiogenesis, these cells exert different activities which require interactions with other cells and with the extracellu-lar environment. It has become evident that this frequently involves galectins since the members of this protein family facilitate interactions between cells and/or glycoproteins via carbohydrate binding. In addition, they can regulate intracellular processes like signaling and splicing via non-carbohydrate interactions. We have previously reported on the role of galectin-1 and-9 in endothelial cell function. Here, we review the current knowledge of these two galec-tins in endothelial cell biology and angiogenesis. In add-ition, we describe the contribution of both galectins to other processes that involve the endothelium, including inflamma-tion and coagulation. Finally, we discuss the challenges for future research in order to better understand how this “sweet ” couple exerts its multifunctional activities within the vasculature