VOLUME 282 (2007) PAGES 27171–27180
This article has been withdrawn by the authors. In June 2017, the Journal raised questions about Figs. 1B, 2C, 3A, 3C, 3E, 4C, 5A, 5C, 6B, 7A, and 7D. The original data and originally submitted figures were not available for evaluation. The authors were able to locate some data for repeat experiments conducted at the time of the original work, which they state support the conclusions of the paper, and offered to prepare new figures based on that data. However, the Journal declined that offer, a decision with which the authors disagree. The authors state that any errors in the construction of figures in the paper do not alter the scientific conclusions of the work, and they stand by the reproducibility of the experimental data and the conclusions of the paper.