Fig. 1.

The role of cell cycle arrest during endothelial sprouting. Upon strong activation of quiescent ECs by a mitogenic signal, a tip cell becomes selected by induction of tip cell gene expression and temporary arrest of the cell cycle. Tip cells activate Notch in adjacent stalk cells which results in inhibition of their ERK activity, thereby maintaining their proliferative status. The arrested tip cells are responsible to guide the sprout towards the mitogenic gradient and are followed by proliferating cells that ensure the growth of the newly formed vessel