At Nature, news of another advance in our ability to control and use stem cells. Based on knowledge gained earlier in 2003, scientists have used chemicals to control the timing of stem cell specialization. This is the beginning of the road to discard some of the very clumsy techniques currently used to this end. A quote: "If we want to make stem cells into therapies, we're going to need cell lines that were never grown in any foreign proteins. This work should help us take stem cells into that clinical setting."