A Nobel prizewinning biologist has retracted two papers written by one of her former postdoctoral researchers after being unable to reproduce their key findings.
Linda Buck, a principal investigator at the Fred Hutchinson Cancer Research Center in Seattle, shared the 2004 Nobel Prize in Physiology or Medicine with Columbia University professor Richard Axel "for their discoveries of odorant receptors and the organisation of the olfactory system".
In 2008 she retracted a paper from the journal Nature, published in 2001, after failing to reproduce its results.
The paper described experiments carried out by Zhihua Zou, a former postdoctoral researcher in Dr Buck's laboratory at the Fred Hutchinson Center and her previous laboratory at Harvard University.
Now Dr Buck has retracted another two papers that feature Dr Zou as first author, which were published in the journals Science in 2006 and Proceedings of the National Academy of Sciences (PNAS) in 2005.
A statement from the Fred Hutchinson Center confirms that Dr Zou had carried out the experiments described in these papers.
The statement says that Dr Buck and her colleagues have also been unable to reproduce key findings in these papers, and have found that figures in the PNAS paper are inconsistent with the original data.
All three papers examined the olfactory system in mice.
"(Dr Buck) regrets any confusion that has resulted from the publication of these papers and thanks the colleagues who painstakingly worked with her to duplicate these experiments and evaluate the data," the statement says.
A spokesman for the Fred Hutchinson Center confirmed that Dr Zou had declined to sign both retraction notices.
Dr Zou's current whereabouts are unknown, and Dr Buck did not respond to requests for comment.
Dr Buck is also a Howard Hughes Medical Institute investigator. Avice Meehan, vice-president for communications and public affairs at the institute, declined to comment on Dr Buck's case, but said: "In general, all scientists at any level work incredibly hard to make sure of the accuracy of their data and therefore take seriously their responsibility to correct the record if it is found to be inaccurate."