A Japanese scientist has called for his own headline-grabbing study on stem cells to be withdrawn from publication, saying its findings had now been thrown into too much doubt.
The research was hailed when it came out in January as a breakthrough that could herald a new era of medical biology.
It was covered widely in Japan and across the world after it was published in the highly reputable science journal Nature.
But since then, there have been reports that other scientists have been unable to replicate the Japanese team's results and that there may have been problems with its data and images.
"It is no longer clear what is right," Teruhiko Wakayama, a professor at Japan's University of Yamanashi who was part of the researcher team, told public broadcaster NHK.
The study, described as game changing by independent experts asked to comment on it when it was published, appeared to show a simple way to re-programme mature animal cells back into an embryonic-like state that would allow them to generate many types of tissue.
The results appeared to offer a promise that human cells might in future be simply and cheaply reprogrammed back into embryonic cell-like cells - in this case cells dubbed Stimulus-Triggered Acquisition of Pluripotency (STAP) cells - suggesting a simple way to replace damaged cells or grow new organs for sick and injured people.
"When conducting the experiment, I believed it was absolutely right," Mr Wakayama said.
"But now that many mistakes have emerged, I think it is best to withdraw the research paper once and, using correct data and correct pictures, to prove once again the paper is right.
"If it turns out to be wrong, we would need to make it clear why a thing like this happened."
A Nature spokesperson said "issues relating to this paper" had been brought to the journal's attention and it was conducting an investigation, but made no further comment.