Significant progress has been made in producing stem cell lines that, for example, participate in the regeneration of damaged nervous tissue. Many human diseases, such as juvenile diabetes (type 1 diabetes), involve malfunctioning genes and environmental triggers. Researchers want to coax embryonic stem cells into becoming healthy insulin-producing cells. These cells might then be transplanted into people with diabetes to produce the insulin they lack. Researchers are also interested in producing stem cells that malfunction exactly like the diseased cells in order to understand fundamental aspects of the disease and also to test treatments. From the Series:HHMI’s Understanding Biomedical Research Series