The ‘missing link’ in the chemical system that enables animal cells to produce ribosomes — the thousands of protein ‘factories’ contained within each cell that manufacture all of the proteins needed to build tissue and sustain life — has been found by a team of biologists. Their discovery will not only force a revision of basic textbooks on molecular biology, but also provide scientists with a better understanding of how to limit uncontrolled cell growth, such as cancer, that might be regulated by controlling the output of ribosomes.