A University of Maryland, Baltimore investigation has resulted in the retraction of four studies examining how maternal diabetes affects neural tube formation. The university’s internal review identified duplicated images and other data integrity concerns, according to the retraction notices.
The papers are part of a set of 25 studies flagged by independent data sleuths, as reported by The Transmitter in June 2025. Since that report, sleuths have identified a total of 44 potentially problematic studies on PubPeer.
“This raises red flags about the validity of the team’s entire body of work,” says Mary Loeken, associate professor of medicine at Harvard University. “My lab has spent time trying to reproduce data from their lab, and we can’t.”
Peixin Yang, endowed professor of obstetrics, gynecology, and reproductive sciences at the University of Maryland, Baltimore, is listed as corresponding author on all four retracted studies and is the only author common to all 44 flagged papers. Two of the retracted studies were co-authored by E. Albert Reece and Wei-Bin Shen, professor and associate professor, respectively, in the same department as Yang; each also co-authored one of the two remaining studies.
The retraction notice for one study, published in 2022 in Communications Biology, states that the editors retracted the article at the recommendation of the University of Maryland, Baltimore. The university also informed the journal that its investigation committee could not confirm the integrity of the data because not all relevant original data was made available for inspection. University policy requires researchers to retain original data and all project records for at least three years after submission of the final report or termination of an award.
The remaining retractions include a 2015 study in Biochemical and Biophysical Research Communications, a 2019 study in Reproductive Toxicology, and a 2020 study in Cell Death and Disease.
Yang, Reece, and Shen did not respond to The Transmitter’s requests for comment for its 2025 report. On September 3, 2026, The Transmitter received a letter from Yang’s attorney, Alexa Millinger of Hinckley Allen in Hartford, Connecticut, demanding that the article be corrected or retracted because it “creates the false impression that Dr. Yang engaged in misconduct” and has harmed his career. The letter also stated that the report’s claim that Robert Cabrera, associate professor of molecular and cellular biology at Baylor College of Medicine, could not replicate Yang’s findings on the benefits of rapamycin was incorrect, because Cabrera used a different mouse model than Yang did.
The Transmitter responded by email on September 14 with questions about the university investigation and the retractions, and requested an interview with Yang. In a second letter dated September 18, Millinger did not address whether Yang agreed with the retractions. She noted that the three retraction notices covering the 2019, 2020, and 2022 studies do not state that Dr. Yang was found to have committed research misconduct.
The letter also included email correspondence between Cabrera and Yang dated July 30, 2025, in which Cabrera confirmed that he and his colleagues “were unable to reproduce a rescue [by rapamycin] in our model, at least in part, because the dosing is developmentally toxic,” citing two other studies showing rapamycin lethality at the same dose. Millinger wrote that Yang declined to be interviewed by The Transmitter. Cabrera, Reece, and Shen did not reply to requests for comment.
The scope and targets of the University of Maryland investigation remain unclear. The university denied The Transmitter’s public-records request for copies of the inquiry or investigation report, citing an “ongoing personnel matter.” Millinger also declined to provide the report, and it remains unknown whether the university contacted any other journals.
When there is questionable methodology and oversight, it calls into question everything that’s come out of their lab.
—Mary Loeken
Representatives from three journals—Science Signaling, the Journal of Neurochemistry, and Developmental Biology—that published flagged papers by Yang and his colleagues told The Transmitter they were unaware of the concerns data sleuths had posted on PubPeer. “This is the first we hear of this,” wrote Ondine Cleaver, editor-in-chief of Developmental Biology, in an email to The Transmitter.
The volume of concerns across so many studies points to a broader problem, says Elisabeth Bik, a data-integrity consultant who initially raised concerns about some of Yang’s studies.
Although the retractions represent a positive step toward correcting the record, other studies with problematic figures have yet to be corrected or retracted, Bik says. “In combination with the university investigation, [journals] did take a pretty hard stance. I think that’s a good outcome,” she added. “But it is still incomplete.”
In particular, Bik points to a 2017 Nature Communications study containing images of developing embryos stained for apoptotic cells that appear to show repeated elements across the tissue. “Clearly, cells are not expected to end up in the same constellations so many times,” she says. “There’s multiple duplications here.” The same study also includes a Western blot image resembling a blot from a previous study depicting a different protein, Bik adds. “This [study] should be retracted.”
“We are investigating concerns, with support from the Springer Nature Research Integrity team, following an established process and will take editorial action as appropriate,” wrote Stéphane Larochelle, editorial director for biological sciences at the journal, in an email to The Transmitter.
“Some concerns were investigated by journals and found not to warrant retraction, correction, or expression of concern,” Yang’s attorney wrote in her September 3 letter. The letter’s sole example was the American Journal of Obstetrics and Gynecology, which concluded that no retraction, correction, or expression of concern was required for a 2013 study after Elsevier’s Research Integrity and Publishing Ethics Centre of Expertise reviewed the concerns and consulted an independent scientist.
Beyond the duplication concerns, Loeken’s lab has been unable to induce the adverse effects of maternal diabetes in the C57BL/6 mouse strain used by Yang’s team, nor reproduce the pathways observed in their model, she says. “In our hands, the same background on the same diet is just resistant to the effects of maternal diabetes,” she says. “When there is questionable methodology and oversight, it calls into question everything that’s come out of their lab.”
