Basal-to-apical cadherin flow at cell junctions.

Stable cell-cell adhesion is essential for maintaining tissue integrity, but cells are also able to relocate, implying the existence of mechanisms for coordinating cell adhesion and movement. Here, we show that, in some transformed lines, cadherin adhesion molecules exhibit a flow-like movement in a basal-apical direction at the cell junction and that this flow is associated with reorganizing actin filaments. Such flow also occurs in normal epithelial sheets, but solely at the junctions formed by moving cells. We propose that cadherin flow may provide a mechanism for facilitating the sliding of the two contacting cell membranes in morphogenetically active cell sheets.