The embattled scientist at the center of a scandal over stem cell research has taken a step back in her efforts to defend her record.

Haruko Obokata became a star in Japan after she developed what was described as a revolutionary way of producing stem cells. She presented the new method in a series of articles published in the journal Nature.

An investigative panel of the Riken research institute concluded in April there were several irregularities in the articles, and recommended that Obokata retract her papers.

Obokata refused, claiming the said irregularities were mistakes she had committed while she hurried to complete the articles.

A Riken spokesperson said on Wednesday that Obokata has agreed to retract the main article, and that she has already signed documents to that effect.

If the journal Nature follows suit, this would in effect erase what had been presented as a major breakthrough in stem cell research.