Guide for a cell-fate decision

摘要

How does an immature cell know how to develop into a specialized one? A fortunate observation has revealed one of the cues that guide precursor immune cells to their ultimate fate. During the development of multicellu-lar organisms, precursor cells mature into specialized cell types, such as muscle cells or blood cells. This cellular differentiation must be carefully orchestrated to generate the correct numbers and types of cells at the right time and place. Unravelling the regulatory circuitry involved is a major goal of developmental biologists. In a striking illustration of Louis Pasteur's famous statement, "Chance favours only the prepared mind", a fortuitous mutation in a mouse has led Kappes and colleagues to a breakthrough in understanding how immune-cell precursors adopt their appropriate cell fate (He et al., page 826 of this issue).