Editorial Expression of Concern to: Nature https://doi.org/10.1038/nature03080 Published online 27 October 2004

Nature is publishing an editorial expression of concern on the article “The netrin receptor UNC5B mediates guidance events controlling morphogenesis of the vascular system”, by X. Lu. et al., to alert the readership that image integrity issues have been raised with some of the data. A report to the Stanford University board concluded that this article reflects evidence of manipulation of research data. We have considered the issues and find that the far-left lanes of the top and bottom panels of Supplementary Figure 2E appear to be duplicated. Given the age of the article there is insufficient information to conclusively assess how the duplication occurred. However, the authors have provided contemporaneous replicates that confirm the validity of the data presented in Supplementary Figure 2E.

Xiaowei Lu, Ferdinand le Noble, Frederic De Smet, Jean-Léon Thomas, Monica Autiero, Peter Carmeliet, Marc Tessier-Lavigne and Anne Eichmann agree with the publication of this statement.

Li Yuan, Quingjan Jiang, Benjamin de Lafarge, Daisuke Sugiyama, Christiane Bréant and Filip Claes have not responded to correspondence about this statement.