Cytoskeleton of WASp-null immature DCs.

WASp-null immature DCs plated for 2 hours on fibronectin lack podosomes and form abnormal lamellipodia. DCs were stained with TRITC-phalloidin (panels A, D, G) or antivinculin (panel B), antiphosphotyrosine (panel E), or anti–Arp2/3 (panel H) antibodies. Merged images are shown in panels C, F, and I. WASp-null DCs are characterized by diffuse f-actin distribution (panels A, D, G,) with predominantly cortical actin staining (arrowhead in panel A). Podosomes are universally absent. Many cells exhibit a hyper-elongated morphology and form abnormal lamellipodia randomly over the cell surface (arrows in panels A, D, G and insert in panel D). Similarly, a diffuse pattern of staining was seen for vinculin (panel B), phosphotyrosine (panel E), and the Arp2/3 complex (panel H). Scale bars represent 10 μm.