Fig. 3. (A) The effects of IGF-IR activation on redistribution of -catenin, -actinin and F-actin. Serum-starved (0 min) MCF-7/IGF-IR/WT cells were treated with 50 ng/ml IGF-I for 5, 15 and 60 minutes, then fixed in 3.7% formaldehyde and stained with a polyclonal antibody to -catenin (a-d), a monoclonal antibody to -actinin (e-h) or TRITC-phalloidin for F-actin (i-l). Arrows show examples of -catenin disappearance from cell-cell contacts (a-c), relocalization of -actinin to the cellular borders (e-h) and reorganization of F-actin and microspike development (i-l) induced by IGF-I. Inset in e, examples of -actinin localized at the tips of stress fibers seen at the free edge of the spread cell. Bar, 10 µm. (B) IGF-I-stimulated reorganization of -actinin and F-actin is blocked when the IGF-IR kinase is inactive. Localization of -actinin (staining with antibody to -actinin) (a-c) and F-actin (staining with TRITC-phalloidin) (d-f) was examined in MCF-7/IGF-IR/DK cells that were serum starved (0 min) and exposed to 50 ng/ml IGF-I for 5 and 60 minutes. Confocal images are representative of three experiments. Bar, 10 µm.

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