Correction to: Nature https://doi.org/10.1038/nature05953 Published online 27 June 2007

In the version of this article initially published, the representative image shown in the lower-left panel of Figure 4e (buffer ethanol HFF-pB MycER) was an unintended duplication of the upper-right panel (a-amanitin 4-OHT HFF-pB). Moreover, a vertical line was inadvertently omitted from Figure 1e to indicate that the 15 samples were loaded on two western blot membranes, run in parallel, and an incorrect image was used for the ORC6 panel. The original and corrected versions of these figures are provided as Supplementary information, linked below. These errors do not affect the conclusions of the manuscript.