Fig. 3. Cytoskeleton interactions in rapidly frozen, fixed samples. Triple label confocal micrographs showing interactions between microtubules (red), F-actin (green) and cytokeratin filaments (blue). (A) Most of the cytokeratin is associated with F-actin cables (arrows). Frequently, the distal ends of microtubules were bent at points of contact with cables of F-actin and cytokeratin, and appeared to track along them (arrowheads). (B) En face view of cytoskeletal interactions and the same view at a tilt of 70°. The interaction of F-actin with cytokeratin (arrowheads) is apparent in both views. (C) The interaction of cytokeratin with F-actin was further examined by quantifying overlap (in pixel number) with and without rotating the channel representing cytokeratin 90° clockwise. The error bar for colocalization with rotation was too small to appear on this graph (P<0.05).