How important the technique will be in the long run is an open question. In the years since human cloning was first attempted, researchers found that they can make patient-specific stem cells by "reprogramming" adult cells into induced pluripotent stem (iPS) cells. That method, which scientists adapted to human cells in 2007, eliminated the need for human eggs and does not involve embryos, two aspects that make SCNT controversial and expensive. But some experiments have suggested that, at least in mice, ES cells from cloned embryos might be of better quality than iPS cells. Now, investigators will be able to compare the two types of human stem cells side by side.