Fig. 4. Immunofluorescence staining of the actin cytoskeleton and vinculin in untreated keratocytes and cells treated with EGTA or gadolinium. Phalloidin staining of the actin cytoskeleton in untreated cells (A) and those treated with EGTA (C) or Gd³⁺ (E). Note in A the prominent centrally located stress fibers (white arrow). (B) Anti-vinculin antibody staining of untreated keratocytes showed a uniform distribution of vinculin puncta throughout the cell that increased in density a short distance behind the leading edge. Anti-vinculin antibody staining of keratocytes treated with EGTA (D) or Gd³⁺ (E) displayed large aggregations of vinculin within focal adhesion-like structures at the lateral rear cell margins (white arrowheads). The cell body appears brighter due to its increased thickness compared with the lamella. Bar, 10 µm.