Cell 157, 1146–1159 (2014)

In vivo, cells often migrate as a collective. For example, cell sheets can move to heal a wound, migrating multicellular strands may form a branching duct in angiogenesis and, in cancer, poorly differentiated multicellular clusters can become invasive. Epithelial cells moving as a group are connected by epithelial cadherin (E-cadherin), a transmembrane protein that, together with other cell–cell adhesion proteins, helps cells maintain polarity and contributes to tissue organization. However, the role of E-cadherin in collective cell migration in vivo has remained unclear. Now, Denise Montell and colleagues show that the transmembrane protein helps stabilize directionally persistent cell migration. By taking advantage of transgenic Drosophila ovary cells expressing E-cadherin proteins that incorporate an optical sensor for mechanical tension (a molecular spring containing a fluorescent protein), the researchers found that the E-cadherin reinforces the activity of a Rho GTPase signalling protein (Rac) for border-cell migration. They conclude that E-cadherin acts as a mechanotransducer in a mechanochemical feedback loop between actin assembly and Rac signalling to stimulate the polarization of cell clusters and their forward-directed movement.