William Saletan at Slate has a very good discussion of the implosion of the stem cell claims from Hwang Woo-Suk's laboratory. :Hwang claimed that large numbers of stem cells were prepared, at good efficiency, from oocytes freely donated (at personal risk) by human women. Good efficiency was a huge deal, because it means reduced risk to future women.
It turns out that pretty much everything in that claim-- except the risk and the women-- is false. An especially heartbreaking twist is that he in fact he exposed women under his administrative control to much, much higher risks than he admitted.
A scientific panel investigating his 2005 study announced that he'd lied about the number of eggs as well as their sources. Hwang said he'd used 185 eggs. A former colleague said he'd used as many as 1,100. Maybe Hwang's 2004 study, in which he claimed to have gotten one stem-cell line from 248 eggs, was a fraud like his 2005 study. Maybe the cost-benefit ratio wasn't 248 eggs to one stem-cell line. Maybe it was 1,100 to zero.
And there is a claim from at least one female junior scientist in her lab that he pressured her to donate. Wow.