From Retraction Watch:
Amy Wagers, an up and coming stem cell researcher at Harvard who made a name for herself as a postdoc early by questioning the work of others, has retracted a January 2009 paper she co-authored in Nature. According to the retraction:
Three of the authors (J.L.S., F.S.K. and A.J.W.) wish to retract this Article after a re-examination of the publication raised serious concerns with some of the reported data. These concerns have undermined the authors’ confidence in the support for the scientific conclusions reported, specifically the role of osteopontin-positive niche cells in the rejuvenation of haematopoietic stem cells in aged mice. Although this matter is under further review, these authors wish to retract the paper in its entirety, and regret any adverse consequences that may have resulted from the paper’s publication. The retraction has not been signed by Shane R. Mayack, who maintains that the results are still valid.