FIGURE 3.

Actin assembly at cadherin-mediated adhesion sites depends on zyxin. A, E-cadherin-decorated adhesion plaques and the leading edge of wild type (WT) cells on E-cadherin-coated substrate. In zyxin-knockdown cells, E-cadherin-positive plaques were disorganized, and E-cadherin puncta were not found at the leading edge. B, wild type and zyxin-knockdown cells plated on E-cadherin substrates permeabilized with saponin and treated with Alexa Fluor 568-labeled actin monomers, followed by fixation and phalloidin staining. Fluorescently labeled exogenous actin decorated actin fibers, tips of actin bundles, and the leading lamellipodial edge in saponin-permeabilized wild type cells. For zyxin-knockdown cells, exogenous actin weakly decorated actin fibers but not actin bundle tips or the leading edge. C, VASP localized to the tips of actin bundles and the leading edge in normal cells. In zyxin-knockdown cells, VASP was not found at the tips of actin bundles, but it remained localized to the leading edge. Scale bars, 10 μm.