Fig. 9. RTK-induced actin dorsal ruffles are formed from c-Cbl containing actin-rich nucleation sites. (A) Confocal fluorescence images of serum-starved NIH 3T3 cells expressing EGFP-actin were recorded every minute following addition of PDGF to the culture medium. The arrowhead indicates a site of actin dorsal ruffle assembly in selected images. Bar, 30 µm. An animated compilation of the individual images is represented in Movie 1 (available at jcs.biologists.org/supplemental). (B) Serum-starved HA-c-Cbl-expressing NIH 3T3 cells were treated with PDGF for 2, 5 or 10 minutes. Single 1 µm apical sections of TRITC-phalloidin (red) and anti-HA staining (green) were visualized individually and as merged images by immunofluorescence confocal microscopy. The arrowheads indicate putative actin nucleation sites. Bar, 30 µm.