Vol. 169, No. 3, May 9, 2005. Pages 515–526.
In the preparation of Figure 6 E, scans for Figure 3 (left panel) that were from the same original film were accidentally used. Original films of these figures have been submitted to JCB and the correct Figure 6 E is provided here. This does not in any way affect the conclusions of the paper. We do apologize for the error.