Issue Archive

The cover shows a megakaryocyte from a WASp null mouse with filamentous actin (labeled red) and vinculin (labeled green). WASp null megakaryocytes do not form podosomes, but rather show actin fibers and diffuse vinculin staining. The authors describe how podosomes form when normal megakaryocytes adhere to collagen matrix or native basement membrane. Podosomes contain highly dynamic actin networks formed when WASp is activated, as well as integrin based adhesions. They function in migration and matrix remodelling via metalloproteases. The authors propose that podosomes facilitate the extension of proplatelet arms through vessel walls for platelet production. See the article by Schachtner et al on page 2542.