Nobel laureate Linda B. Buck, a former professor at Harvard Medical School, retracted on Friday two academic papers about olfactory receptors after some of the data was found to be irreproducible.

Buck, currently an affiliate professor in the department of physiology and biophysics at the University of Washington in Seattle, retracted the papers from the Proceedings of the National Academy of Sciences and Science, respectively published in 2005 and 2006.

Buck served as a neurobiology professor at Harvard Medical School from 2001 to 2002, according to her curriculum vitae. In 2004, she was named a co-recipient of the Nobel Prize in Physiology or Medicine for her studies on the connections between the nose and the brain.

The recent retractions do not mark the first time that Buck has been subject to scrutiny for questionable research. In 2008, she retracted a paper published in Nature in 2001—research for which had been conducted at Harvard.

The incident prompted the University to spearhead an investigation into any evidence of misconduct, according to Medical School spokesperson David J. Cameron.

After the 2008 retraction, Buck and her colleagues returned to earlier academic papers, attempted to reproduce “key findings,” and were unable to do so, according to an e-mailed statement from Kristen L. Woodward, senior media relations manager for Buck’s current employer, the Fred Hutchinson Cancer Research Center.

Buck’s team, which attributed the errors to her former postdoctoral researcher Zhihua Zou’s experiments, also found figures in the Proceedings paper that were inconsistent with the original data, according to Woodward.

“She 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,” Woodward said.

Zou signed the retraction for the 2001 Nature article two years ago, but he has declined to sign off on the two recent retractions. His former employer and various news organizations have reported that Zou has returned to China.

As recent as last month, news broke of Harvard Psychology Professor Marc D. Hauser’s eight instances of scientific misconduct. But Michael E. Greenberg, head of the neurobiology department at Harvard Medical School, said he doubts that academic misconduct is an ongoing trend among researchers.

“Most often it just turns out to be that science is not that rigorously done,” said Greenberg, who added that he merely knew Buck as a colleague at Harvard. “When people try to reproduce it, they realize that the person was fooling themselves.”

Harvard Medical School Assistant Professor Stephen D. Liberles ’94, a former postdoctoral fellow in Buck’s lab at Harvard, praised Buck for her commitment to scientific accuracy.

“These retractions are a testimony to her integrity and transparency,” he said.

“The scientific process will benefit by these disclosures,” Liberles said.

Greenberg said that Buck’s retractions will benefit the scientific community, for other researchers often read papers published in journals and reproduce or modify the experiments for their own purposes.