VOLUME 279 (2004) PAGES 26627–26634
This article has been withdrawn by the authors upon request from the Journal. The Journal raised questions regarding Fig. 4. The authors were able to locate original autoradiographs and state that during assembly of this panel, an actin lane was duplicated. The authors assert that all of the results reported in this article are valid, some of which have been independently validated in the literature (Burkart et al. (2012) J. Cell Biol. 197, 37).