By Rebecca Morelle
Science reporter, BBC News
The fall from grace of cloning superstar Hwang Woo-suk rocked the scientific world.
Dr Hwang went from national hero to national disgrace
The South Korean scientist had rocketed to international fame after claiming to be the first to have created stem cell lines from cloned human embryos, something experts around the world had been trying - and failing - to do for years.
But last year, after rumours abounded about the credibility of his results and dodgy dealings in his procurement of human eggs, the prestigious journal Science concluded his work was fraudulent and immediately retracted his papers.
It was the beginning of the end for Dr Hwang: he lost his post at Seoul National University; his state title "Supreme Scientist" was stripped; he was banned from carrying out human cloning work; and he is now on trial charged with fraud, embezzlement and breach of bioethics.
While the fallen researcher's future looks uncertain, 12 months on, "Hwang-gate" seems to have left a lasting legacy elsewhere.
'Back to square one'
"In terms of the science, it has really taken us back to square one," explained Dr Stephen Minger, a stem cell researcher from King College London, UK.
"Nobody has got close to doing what Dr Hwang claimed to have done."
While a UK research group has managed to create a cloned human blastocyst (an early stage embryo), it was unable to derive embryonic stem cells from it. Other attempts to create cell lines around the world have met with a similar fate.
And Dr Minger fears we may stay at square one for some time yet.
He said: "Hwang seemed to have all the resources and an endless supply of human eggs to use.
"But here and elsewhere people cannot push this field forward because there is a profound shortage of eggs - and this is a major problem."
Feb 2004 Hwang Woo-suk's team declare they have created 30 cloned human embryos and extracted stem cells
May 2005 Team says it has made stem cell lines from skin cells of 11 people
Nov 2005 Hwang apologises for using eggs from his own researchers
15 Dec 2005 A colleague claims stem cell research was faked
23 Dec 2005 Academic panel finds results of May 2005 research were fabricated
10 Jan 2006 Science retracts Hwang's 2004 and 2005 papers
20 March 2006 Hwang sacked from SNU
12 May 2006 Charged with fraud and embezzlement
The impact is not limited to stem cell research - the shockwaves have reverberated around science as a whole.
"Any story of scientific fraud causes concern and panic amongst scientists," Professor Robin Lovell-Badge, head of developmental genetics at the National Institute for Medical Research in London, told the BBC News website.
"People start asking questions like: 'How do I know members of my lab aren't faking data?' or: 'Is my boss's interpretation of my data right?'"
While scientific fraud is not new, he adds, Dr Hwang has brought it to the fore.
Hoping they can learn from the affair, scientists are still trying to get to the bottom of the Korean scientist's behaviour.
Writing in the Journal of Medical Ethics, bioethicist Professor Julian Savulescu, from Oxford University, said: "Hwang credited his 'success' to plentiful funds, abundant oocytes (eggs), and a supportive - mostly unregulated - political and legal environment.
"[He] met with many pressures but few constraints; the choices he made at each juncture made his decline inevitable."
But while the hows and whys are being untangled, scientists are asking if this could happen again, and if so, what can they do to prevent it.
Proposals such as international codes of ethical practice, courses for students and scientists in detecting fraud and more independent monitoring in institutions have been put forward, but scientific journals too are stepping up their efforts.
In a recent editorial, Donald Kennedy, editor-in-chief of Science, said an investigation into how Dr Hwang's fraudulent papers slipped through their publication process had given them "tough messages about what Science should do".
He wrote: "The environment for science now presents increased incentives for the production of work that is intentionally misleading or distorted by self-interest."
It seems that peer review - the process by which journals get independent experts in the field to check the quality of a paper to deem it worthy or not for publication - may no longer be enough.
"High risk" papers - research that is of significant public interest, has unexpected or counterintuitive results - submitted to Science now faced extra editorial scrutiny, explained Dr Kennedy.
These checks could include examination of the primary data, specification of each author's role and closer inspection of digital images to check for tampering.
Dr Ritu Dhand, chief biological sciences editor of Nature, agreed the scandal had changed the way journals looked at some research.
"This has made us much, much more wary," she told the BBC News website.
The journal would pass a more critical eye if a paper came to it purporting to have done what Dr Hwang claimed he had done, she said.
The Korean public adored Hwang
"It's better to be safe than sorry - the science has to be absolutely watertight."
The story has been described by some as like a "Greek tragedy".
In South Korea, Dr Hwang was adored and treated as a national icon.
The revelation hit South Koreans hard, explained Professor Song Sang-yong of the Korean Academy of Science and Technology. Dismay and disbelief pervaded. It was a national tragedy from which the country was still recovering, he added.
And the atmosphere of mistrust it had generated was something science would need to learn from, said Dr Minger.
"One year on, we are a lot more sober and less 'starry-eyed'," he reflected.