Fig. 4. Xin repeats are excluded from lamellipodia. B16F1 cells were transfected with XR1-16-EGFP, plated on laminin and analysed using phase-contrast and fluorescence video microscopy. (A-H) Representative frames derived from a movie recorded over 15 minutes as indicated. The black lines in B,D,F,H outline the border of the distribution of XR1-16-EGFP within the cell. In I,J, the distribution of Xin repeats (I) is compared with that of actin filaments (J) in the same cell stained with phalloidin. Xin repeats bind to the contractile actin filament bundles and focal adhesions in the body of the cell (G, arrowheads). By contrast, the repeats are virtually absent from the dynamic actin structures in the lamellipodium (I,J, arrows). Scale bar, 20 µm.