Dying on cue

William Earnshaw and colleagues wanted to plumb the intricacies of cell birth, but they ended up discovering a vital tool for studying cell death in vitro (Lazebnik et al., 1993). The sequence of events in apoptosis remained uncertain at the time, recalls Earnshaw (now at the University of Edinburgh in the UK), because suicidal cells die asynchronously. “You could never have a tube of cells all undergoing apoptosis at the same time,” he says. This made it difficult to pinpoint the biochemical details of each step.

Earnshaw's group was hoping to crack a different question: how the cell's chromatin condenses during mitosis. To study the process, they had devised a cell-free system containing cytoplasm from dividing liver cancer cells. Nuclei bathed in these extracts appeared to begin...