Elaine Kurtenbach, The Associated Press Published Wednesday, April 9, 2014 7:55AM EDT

TOKYO -- The Japanese scientist accused of falsifying data in a widely heralded stem-cell research paper said Wednesday the results are valid despite mistakes in presentation of the results.

Haruko Obokata, 30, struggled to maintain her composure during a televised news conference packed with hundreds of reporters, but insisted she did not tamper with the data to fabricate results. She said she did not agree with retracting the research that appeared in the scientific journal Nature.

The phenomenon of ordinary cells transforming into stem cells under the influence of external stimulus was "confirmed many times for a fact," Obokata said at the press conference in the western city of Osaka. She said she could replicate her results again if allowed back into the lab to do so.

She has contested allegations of research malpractice made by a panel of scientists at the government-funded Riken Center for Development Biology, where she is employed.

Obokata said Riken had advised her not to speak publicly about the controversy. The event Wednesday, which lasted for over two hours, was her first public appearance in weeks and was made against doctors' orders after seeking hospital treatment Monday.

"I wasn't able to sleep well and was feeling worse and worse," she said. "I take this responsibility severely. I am deeply sorry."

Obokata apologized repeatedly for having used the wrong images and having altered an image in a report on using a simple lab procedure to grow tissue for treating illnesses such as diabetes and Parkinson's disease.

In an emailed statement, Riken reiterated Obokata's right to an appeal of its findings.

"Riken will give due consideration to the appeal in accordance with our regulations," it said.

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Maligned stem cell researcher insists results valid