Fig. 1. Effect of dominant-negative Cbl expression on RTK-induced cytoskeletal dynamics. (A) Truncation of c-Cbl at amino-acid residue 480 uncouples the N-terminal TKB and RING domains from the numerous C-terminal docking sites. (B) Wild-type, HA-c-Cbl-and HA-480-Cbl-expressing NIH 3T3 cells were lysed and aliquots of the lysates were subjected to SDS-PAGE and western blotting with anti-c-Cbl and anti-HA antibodies as indicated. (C) Serum-starved wild-type (panels 1, 2 and 3) and 480-Cbl-expressing NIH 3T3 cells (panels 4, 5 and 6) were treated with PDGF for 5 minutes. Merged confocal fluorescence microscopy Z-section stacks of phalloidin (red) and anti-tubulin (green) staining are shown in panels 1 and 3, whereas 1.5 µm thick apical sections are shown in panels 2 and 5 for phalloidin staining and panels 3 and 6 for anti-tubulin staining. A PDGF-induced actin aggregate in wild-type cells is indicated by the narrow arrowhead in panel 1. An actin dorsal ruffle is indicated by the broad arrowhead in panel 4. The scale bar represents 20 µm.