A growing number of scientists say independent testing is needed to resolve charges that South Korean researchers fabricated experimental findings in two landmark papers on stem cells derived from cloned human embryos.

		Previous coverage Retraction sought of stem cell paper (12/14/05) Clone pioneer apologizes for ethics breach, resigns posts (11/25/05) Pitt scientist leaves joint stem-cell project (11/13/05)

A group of eight leading researchers, led by Ian Wilmut, the Scottish biologist who cloned Dolly the sheep eight years ago, is urging Woo-Suk Hwang and his cloning team to submit samples of the embryonic stem cell lines and of the cell donors for genetic analysis.

"For me, it's just hard to imagine why they would not just put this to rest," one of that group, Robert Lanza of Advanced Cell Technologies in Worcester, Mass., said yesterday. Independent testing could verify the findings in just a few days, he said.

Revelations last month of ethical lapses in obtaining donor eggs and subsequent acknowledgement of what appeared to be sloppy editing had been "very embarrassing," but did not change the conclusions of the research papers, said Rudolph Jaenisch, a stem cell researcher at the Massachusetts Institute of Technology.

Charges by Dr. Hwang's co-author, reproductive biologist Gerald Schatten of the University of Pittsburgh School of Medicine, that some of the data may have been fabricated is quite a different matter.

"That goes to the heart of the conclusions," Dr. Jaenisch said. "I think everything needs to be verified by an independent laboratory."

In a letter this week to the journal Science, Dr. Schatten suggested that his co-authors retract a paper published last June and asked that his name be removed as an author.

The independent testing being urged by fellow researchers would be over and above the efforts promised by officials at Seoul National University to re-evaluate Dr. Hwang's data and the inquiry into Dr. Schatten's role launched last week by the University of Pittsburgh's office of research integrity.

Pitt's inquiry panel met for the first time yesterday morning. Among the issues is whether Dr. Schatten had a sufficient knowledge of the procedures and findings that were the basis of a scientific paper for which he was a senior author.

Each institution has a responsibility to look into the matter, said John D. Gearhart, a stem cell researcher at Johns Hopkins University School of Medicine.

"They have to clean up their house," he said. But each also faces peculiar pressures involving high-profile researchers, particularly the university officials in Seoul.

"This guy is a god in that country," he said of Dr. Hwang, "and this is really going to sting."

Dr. Hwang, who has not responded to e-mail requests for comment, first stepped into the limelight two years ago when he reported in Science that he had cloned a human embryo and derived a line of embryonic stem cells from it.

Last spring, in another Science paper co-authored with Dr. Schatten, he reported establishing 11 human embryonic stem cell lines for a variety of diseases, also from cloned embryos.

"We were all very excited when this happened," said Dr. Lanza, noting that the papers suggested therapeutic cloning was possible and clinical trials might be in the offing.

But it all unraveled this fall. On Nov. 12, Dr. Schatten announced he was ending his collaboration because he was convinced that Dr. Hwang had lied to him about how donor eggs were obtained.

Dr. Hwang subsequently acknowledged that eggs had been donated by two of his research subordinates -- an ethical concern because of the potential for coercion -- and that donors had received payments for direct expenses.

Dr. Schatten had not been involved directly in the experiments, but said he helped analyze the data and write this year's Science paper.

At the time he ended the collaboration, Dr. Schatten also had notified Science of an error in a data table in the Science paper, though it did not affect the paper's conclusions. And after anonymous Web sites noted curious similarities between some images in the published paper, Dr. Hwang informed Science editors on Dec. 4 that some duplicate images had been mistakenly sent for publication.

The revelation of yet another error prompted Arthur S. Levine, senior vice chancellor for health sciences at Pitt, to call for an inquiry.

Jerome Rosenberg, Pitt's research integrity officer, said the inquiry panel is exploring whether Dr. Schatten and other Pitt employees -- several former members of Dr. Hwang's lab now work with Dr. Schatten at Magee-Womens Research Institute -- were guilty of negligence or scientific misconduct.

This week, Dr. Schatten sent another letter to Science:

"Over the weekend, I received allegations from someone involved with the experiments that certain elements of the report may be fabricated," he wrote.

He said he had recommended to his co-authors that the paper be retracted and asked Science to remove his name as an author.

Editors of Science said scientific papers can only be retracted by the agreement of all authors and that no single author can withdraw unilaterally.

As a senior author, Dr. Schatten should have known the experimental data "inside and out," Dr. Gearhart said.

That's one of the issues the Pitt inquiry panel is tackling, said Dr. Rosenberg.