Fig. 5. Cytokeratin—F-actin interactions change over time. Double-label confocal micrographs showing F-actin (red) or cytokeratin (green) rapidly frozen at increasing time intervals following warming of extract to room temperature. Immediately after warming (0'), F-actin cables are not present and cytokeratin was found as particulates on the substrate. At 5' and 10', cytokeratin filaments are present, and invariably associated with F-actin cables. By later time points (20'), both F-actin and cytokeratin cables are thicker, and cytokeratin cables are frequently found without associated F-actin (arrowheads).