α-Catenin regulates cell edge protrusion-retraction cycles and cytoskeletal organization. (A) Left: Immunoblot for α-catenin in lysates taken from WT MEFs, α-catenin KD MEFs, and α-catenin KD MEFs expressing WT GFP-α-catenin. Right: Immunoprecipitation for vinculin followed by immunoblot for α-catenin; below is a blot for vinculin from the cell lysates. WB, Western blot. (B) Left: Kymographs of the cell edge taken from time-lapse videos of early spreading by WT and α-catenin KD MEFs showing regular protrusion-retraction cycles in the former and extensive ruffling in the latter. Right: quantifications of the distances traveled during the protrusion and retraction phases by WT MEFs, α-catenin KD MEFs, α-catenin KD MEFs expressing WT GFP-α-catenin, and α-catenin KD MEFs expressing GFP-α-catenin L344P. WT and GFP-WT cells display longer protrusions than retractions, whereas KD and L344P cells do not, consistent with ruffling. n > 30 cycles from at least eight cells in each case. (C) F-actin staining (phalloidin) in vinculin^−/− MEF cells expressing WT GFP-α-catenin, GFP-α-catenin L344P, and GFP-α-catenin L344A. The yellow arrows point to actin aggregates near the cell center. Source data are available for this figure: SourceData FS3.