Data in a widely heralded stem cell research paper were falsified, a Japanese-government-funded laboratory said Tuesday, as the lead researcher in the study denied any wrongdoing.

The research from the Riken Center for Developmental Biology in Kobe, western Japan, had been hailed as a possible breakthrough for growing tissue to treat illnesses such as diabetes and Parkinson’s disease, using a simple lab procedure.

But significant discrepancies in research published in January in the scientific journal Nature led a panel of scientists at Riken to conclude they stemmed from falsified data.

They said researcher Haruko Obokata, the lead author of the paper in Nature, had manipulated or falsified images of DNA fragments used in the research. The researcher said she intends to appeal.

In a news conference, Riken Director Ryoji Noyori said that after allowing for an appeal, disciplinary action would be taken, including calling for retraction of the suspect paper.

The institute said it would take months to determine whether the stem cell findings are valid, regardless of any questions about the data. Obokata said the findings are genuine.

The scientists investigating the case said three co-authors of the papers had not falsified the data.

Researchers in Boston and Japan conducted the experiments in using a simple procedure to turn ordinary cells from mice into stem cells by exposing cells from spleens of newborn mice to a more acidic environment than they are used to. Cells from other tissue of newborn mice appeared to go through the same change if exposed to any of a variety of stressful situations, the researchers said.