Fig. 7. Rac1 activity is required for assumption of a fan shape by 3ß1-expressing MK cells. MK^+/+ cells (A-F) or MK3 cells (G-L) expressing either dominant negative Rac1N17 (A-C,G-I) or GFP (D-F,J-L), as indicated. F-actin staining was performed using TRITC-conjugated phalloidin. Infected cells were visualized by GFP fluorescence. Corresponding phase-contrast images are shown for each field. Bar, 10 µm.