Identification of the domains of IRSp53 required for podosome formation.

<p>(A) The podosomes of cells expressing IRSp53 fragments. NIH-Src cells transfected with myc- or GFP-tagged expression vectors were observed by staining with anti-myc (green) or direct fluorescence of GFP, respectively. The cells were also stained with rhodamine-phalloidin (red) to visualize actin filaments. Scale bar, 20 µm. (B) Percentages of cells with podosomes expressing various IRSp53 mutants. The effects of the dominant-negative forms of Rac1 (Rac1 T17N) and Cdc42 (Cdc42 T17N) are also included. Data are means±SD from three independent experiments. Approximately 100 cells were counted in each determination. *<i>P</i><0.05 versus myc-IRSp53 expressing cells (Student's <i>t</i> test). The domain structures of the construct used in this study are indicated in Fig. 5E.