Medical researchers were shocked to discover that virtually all human embryonic stem cell lines being used in 2005 were contaminated. Animal byproducts used to line Petri dishes had left traces on the human cells. If those cells had been implanted in a human body they likely would have been rejected by the patient's immune system.

Together with colleagues in Barcelona, researchers at the University of North Carolina at Chapel Hill have generated a complete map of the areas of the genome that control which genes are "turned on" or "off." The discovery, made in pancreatic islet cells, opens new avenues for understanding the genetic basis of type 2 diabetes and other common illnesses.

University of Michigan researchers have shown that tension on DNA molecules can affect gene expression---the process at the heart of biological function that tells a cell what to do.