Regenerative medicine and tissue engineering require the ability to create cells to order, and researchers are presently working to produce that infrastructure. Illustrative work to that end via EurekAlert!: "a major stumbling block to developing new treatments has been the difficulty scientists have faced ensuring the stem cells turn into the type of cell required for any particular condition - in the case of diabetes, pancreatic cells. ... Unprompted, the majority of stem cells turn into simple nerve cells called neurons. Less than one per cent of embryonic stem cells would normally become insulin-producing pancreatic cells, so the challenge has been to find a way of producing much greater quantities of these cells. ... The team found that the transcription factor PAX4 encouraged high numbers of embryonic stem cells - about 20% - to become pancreatic beta cells with the potential to produce insulin when transplanted into the body. Furthermore, the scientists for the first time were able to separate the new beta cells from other types of cell produced using a technique called 'fluorescent-activated cell sorting' which uses a special dye to colour the pancreatic cells green."