2002: Catherine Verfaillie of the University of Minnesota's Stem Cell Institute publishes a groundbreaking study on the medical potential of adult stem cells from mice.

2006: The British magazine New Scientist, while preparing an article on Verfaillie's studies, questions the accuracy of some of her research data.

2007: A panel of university experts concludes that one of Verfaillie's research processes was "significantly flawed."

2008: The U concludes that a 2001 study by Verfaillie contained falsified data and asks that it be retracted by the medical journal that published it. The investigation clears Verfaillie of misconduct, pinning the fault on a former graduate student, but blames Verfaillie for "inadequate training and oversight."

2009: New Scientist challenges the accuracy of research by another scientist at the Stem Cell Institute. The U begins another internal investigation.