Good news from EurekAlert: "Once an embryo is a few days old, the stem cells start to differentiate into particular tissue types, and pluripotency is forever lost. But if stem cells are extracted, researches can keep them in this pluripotent state indefinitely, preserving them as a kind of cellular blank slate. The therapeutic goal then is to take these blank slates and coax them into, say, liver or brain tissue. But in order to guide them out of pluripotency with efficiency, we need to know what keeps them there to begin with. ... We've uncovered a key part of the wiring diagram for these cells and can now see how this is accomplished." Oct4, Sox2, and Nanog proteins are the master regulators. "These findings provide the foundation for learning how to modify the circuitry of embryonic stem cells to repair damaged or diseased cells or to make cells for regenerative medicine."