VOLUME 281 (2006) PAGES 13604–13611
This article has been withdrawn by the authors. In June 2017, the Journal raised questions concerning Figs. 2B, 3B, and 5A. The original data and originally submitted figures were not available for evaluation. Regarding Fig. 2B, the authors were able to locate a repeated experiment performed at the time of the original work, which they state confirm the results. Regarding Figs. 3B and 5A, the authors are not convinced that any duplication occurred, and they were able to provide to the Journal data from multiple partial repeat experiments performed at the time of the original work, which they state confirm the results. The authors offered to publish substitute figures based on the repeated experiments and, alternatively, offered to repeat the experiments. However, the Journal declined both of these offers, a decision with which the authors disagree. The authors stand by the reproducibility of the experimental data and the conclusions of the paper. The paper, with confirmatory data supporting the results, can be obtained by contacting the authors.