PLOS One slaps four papers with expressions of concern for overlapping control data

Four papers from a team of researchers in Japan have received expressions of concern for overlap in control samples, data, study design and statistical analyses. The publisher of the articles says it has closed its investigation. 

The notices were published in PLOS One from July 31 to August 3 to inform readers of “study design concerns” and to provide additional supplementary data. They also cite a pair of related papers in other journals for the same problems, but those articles remain unmarked. 

Masaya Oki, a professor of applied chemistry and biotechnology at the University of Fukui in Japan, is the corresponding author on all six papers. Each discusses the effects of a different gene inhibitor on cataracts taken from rat eyes. While the authors used multiple methods to study these effects, the EOCs concern the results obtained using microarrays to compare lens samples. 

The nearly identical notices cite concerns about overlapping samples, datasets, and the fact that the papers all use the same ethical approval number. According to the EOCs, “the corresponding author stated that each article is interconnected and used data from the same control and galactose microarrays in order to compare samples collected at different time points, whilst the inhibitor samples in each article differ.”

However, the investigation at PLOS One reached a different conclusion about the reliability of this approach. The EOCs state, “based on input received from the PLOS One Editorial Board and a statistical reviewer, PLOS concluded that the microarray study design and data analyses were not performed to a high technical standard and call into question the reliability of the microarray results.” The notices list multiple issues with the study design and statistical analyses performed on the data. 

Before providing additional supplementary data to back up the claims, the EOCs state, “PLOS concluded that the reliability of the microarray data is in question given the study design concerns, but the main conclusions in [this paper] are supported by the RT-qPCR results which are not critically dependent on the microarray results and which validated the microarray findings pursued in [this paper] for follow-up studies.”

While publishers can use expressions of concern as an interim notice to readers about a potential problem with a paper, “in this case, PLOS has concluded the editorial investigation into the concerns raised, and the EOC notices are published as a permanent editorial outcome,” Maria Zalm, publication ethics team manager at the company, told Retraction Watch.

Three of the PLOS One papers were published in 2022, and the fourth in February 2024. “PLOS first became aware of the concerns with these articles in late April 2024,” Zalm told us. Zalm declined to state how the publisher became aware of the concerns. None of the papers has been flagged on PubPeer.

The EOCs cite two other papers not published at PLOS One. A 2019 article appeared in Scientific Reports, published by Springer Nature. The second was published in September 2024 in Genes to Cells, published by Wiley. Spokespeople from both companies confirmed they recently began investigations into the research.

“The authors responded to all queries raised by PLOS to address the issues raised with the articles and collaborated with PLOS to ensure the accuracy of the resulting notices,” Zalm said.

Oki declined to comment on the record, telling us, “we were required to promise that we would not respond to any further inquiries on the matter.” In a followup email, Oki said “it was the journal” that made the request.

David Knutson, head of communications at PLOS, told us the journal “made no such request of the authors.”

The six papers have collectively been cited 72 times according to Clarivate’s Web of Science.

Like Retraction Watch? You can make a tax-deductible contribution to support our work, follow us on X or Bluesky, like us on Facebook, follow us on LinkedIn, add us to your RSS reader, or subscribe to our daily digest. If you find a retraction that’s not in our database, you can let us know here. For comments or feedback, email us at [email protected].