In the fledgling world of embryonic stem cells, where Woo Suk Hwang of Seoul National University once took the field by storm, scientists who had faltered behind him are just now realizing why: his data were faked. Hwang's acknowledgment of fabrication and under-the-table dealings late last year eliminated from the record one of the field's most promising therapeutic advances--patient-specific stem cell lines--and left many wondering how powerfully this crisis, one that ethics expert Jonathan Moreno of the University of Virginia calls "the greatest conduct disaster in microbiology," may swing the debate over embryonic stem cells (ESCs).

Starting in 2004, Hwang and his colleagues reported stunning advances in somatic cell nuclear transfer (otherwise known as therapeutic cloning), in which the nuclei of adult cells were put into embryos to create stem cell colonies specific to patients. Following last year's revelations that only one of those successes actually occurred--the cloning of a dog--the stem cell community has been struggling to gauge the impact.

At worst, says Alan Colman of ES Cell International in Singapore, "it may cause a tainting of the whole field" if the public confuses the tiny corner of research spearheaded by the Koreans with mainstream work on embryonic stem cells harvested from preestablished lines. That work, the only kind funded by the U.S. government, is not as scientifically or ethically precarious because it does not demand new human eggs. ESC research opponent Andrew Fergusson, president of the Center for Bioethics and Human Dignity, corroborates that outcome, predicting that this debacle will "make the average American less likely to support stem cell research" when financial investments, ethical tightrope walking and lack of scientific proof are taken into account. Such a reversal would be disastrous for U.S. researchers, who rely on the public's enthusiasm--translated into private donations and state-sponsored legislation--rather than federal dollars for support.

But at best the scandal has only "set back the clock" on therapeutic cloning, so that "the field is wide open," says Evan Snyder of the Burnham Institute in La Jolla, Calif., who will continue to pursue research similar to that of the Koreans. Tailored stem cell colonies are considered a crucial way "to study pathology in a petri dish, so you can make all kind of advances that are hard to predict otherwise," explains Douglas Melton, co-director of the Harvard Stem Cell Institute; he says that the obstacles to succeeding where Hwang failed are principally technical, not biological, and that the money being poured into the work is still money well spent.

Whether funding sources will agree remains to be seen. Moreno points out that "the effect won't be as great as might have been the case a year ago," because four states--California, Connecticut, Illinois and New Jersey--have already made a financial commitment to embryonic stem cell work. (Still, New Jersey recently tabled its 2005 stem cell measure.) As for institutional backing, opines bioethicist Arthur Caplan of the University of Pennsylvania, "patient advocacy isn't budging"--certainly a positive note for the embattled science.

Beyond the future of research, the bigger issue may be how the scientific community will address the apparent lack of safeguards against misconduct. Defenders note that Hwang's faulty science would have been caught eventually, when the experiments defied replication by other, independent parties. And in terms of ethical responsibility, they point to the National Academy of Sciences's guidelines, published voluntarily seven months before Hwang's fraud, and to the fact that it was caught by other scientists, as evidence of the community's self-correcting nature.

Yet the peer-review process--required to publish papers in scientific journals--is not designed to expose outright wrongdoing, even the staunchest advocates have to admit. They agree that had whistle-blowers not come forward, Hwang's falsified data and unethical means of egg procurement might have gone unnoticed. And this revelation, in turn, has recast the spotlight on missing legislation at home and abroad.

"It's become the Wild West out there, with each state doing what it pleases," says Steven Teitelbaum of Washington University in St. Louis, who has lobbied for changes in the Bush administration policy. "We have nothing that assures the research will be done ethically--laws should be passed on this." Others, including Caplan, believe that international treaties will be necessary to head off concerns over egg sales. One danger is that without oversight, nations may pull away from the international stem cell exchange and cooperative research altogether. "If there are differences in standards, countries could turn isolationist," Colman says.

That slowdown is certain to occur in at least one arena. After seeing how Gerald Schatten of the University of Pittsburgh, a senior co-author who purportedly played a minor role in Hwang's experiments, was carried along in the downward spiral, Moreno says, "people will think twice about collaborating." Potential co-authors of the future may painstakingly assess a project before consenting to give their names--and journals may be pressed to monitor more carefully the contributions of all involved. As for scientific relations with South Korea specifically, Snyder reports that "some of our philanthropic support sent a message: essentially, 'Don't work with the Koreans.' They have no problems with the field, but the Koreans are radioactive now."

Changes there may have to start from the ground up, where the culture is "saturated with distorted patriotism and ultra-nationalism," wrote one Seoul National University professor in a Korea Herald editorial. Some even predict a pendulum shift in the way science is conducted. "We'll see very strict regulation set up in Korea," Caplan speculates. "They'll overemphasize high standards."

For all the questions raised by the offenses, many in the business hope that the public can simply home in on the true offender: Hwang himself. Scientists doubt that the man's reputation will ever recover, because "he had every opportunity to come clean, but he went on blaming other people," Colman points out. Ultimately, Moreno asserts, "this is not about profound questions or about ethical line crossing for research. It's about something we can all agree on: we shouldn't lie."