After steadfastly defending her work against accusations of falsified data and an official misconduct ruling, the lead author on two controversial stem cell papers published this year in Nature has reportedly agreed to retract one of them. Earlier today, Japanese media began reporting that stem cell researcher Haruko Obokata of the RIKEN Center for Developmental Biology in Kobe, Japan, is willing to retract a paper concluding that so-called STAP stem cells can form a wide variety of tissues, but does not intend to retract the paper describing how to make those stem cells.

Along with colleagues in the United States and Japan, Obokata described online on 29 January in Nature a new method for reprogramming mature cells into stem cells. The technique, called stimulus-triggered acquisition of pluripotency (STAP), appeared amazingly simple—exposing mature cells to an acid bath or physical pressure could seemingly switch them into stem cells. But it drew almost immediate accusations of image manipulation and plagiarism. In April, an investigating committee at RIKEN ruled that the issues with the papers constituted research misconduct, but did not call for their retraction. Obokata’s lawyer now tells the Japanese press that she will retract a secondary paper describing what STAP cells can develop into, but not the methods article, in which the committee had identified image manipulation and data apparently reused from Obokata’s graduate thesis.

Obokata has argued that the problems with the papers were the result of inexperience, not deliberate wrongdoing, and that STAP cells really do exist. After the ruling, she issued a statement saying that she intended to appeal the judgment.

The Japan Times reports that at least two of Obokata’s 10 co-authors on the letter have also agreed to the retraction, including Teruhiko Wakayama of the University of Yamanashi, the paper’s last author. Wakayama has been consistently critical of the work, telling the Japanese press he had “lost faith” in the paper, and calling for its retraction. However, Charles Vacanti of Brigham and Women's Hospital (BWH) in Boston, last author on the main article and Obokata’s former adviser, has continued to defend the research. A BWH representative told ScienceInsider that Vacanti had no comment on Obokata’s announcement.

Willingness to retract one paper but not the other is a sign of the lingering disagreement among the co-authors, says stem cell researcher Paul Knoepfler of the University of California, Davis. He argued in a blog post earlier this week that Nature should editorially retract both. “It would be naive to think that only the letter [the second paper] can be retracted and that the [methods] article will remain with the STAP cell narrative overall having any legitimacy,” he told ScienceInsider in an e-mail. “I believe the ultimate fates [of the two papers] are tightly tied together.”