Nature 440, 702–706 (2006); doi:10.1038/nature04585

In this Letter, some PCR input panels contain duplicated bands (Figs 1b and 2a; and Supplementary Figs 4 and 6a). In Fig. 2e, the ARF promoter panel is a duplicate of the RD panel in Supplementary Fig. 8c. The raw data were not available to verify the data. Given these issues, the authors wish to retract the Letter. The authors deeply regret these errors and apologize to the community. Peter Klatt, Sonia Delgado, Esther Conde, Fernando Lopez-Rios, Montserrat Sanchez-Cespedes, Juan Mendez, Francisco Antequera and Manuel Serrano agree with the Retraction of the Letter. Susana Gonzalez could not be reached.