The cloning technique, called somatic cell nuclear transfer (SCNT), is the same one used to clone Dolly the sheep 17 years ago. Scientists remove the nucleus from an egg cell and then fuse the remaining cell material with a cell from the individual to be cloned. They then give the fused cell a signal to start dividing, and when things go right an embryo develops. Scientists have used SCNT to clone mice, pigs, dogs, and other animals, but human cells proved trickier to work with. Years of trying—and a high-profile fraud—yielded nothing more than a few poor-quality embryos, unable to produce ES cells.