In Mitchison and Salmon, Mitosis: a history of division. Nature Cell Biol. 3, E17–E21 (2001), Figure 3 should read 40μm long, Figure 3c should read 20μm long, Figure 3d should read 2-3 μm min−1 and 40μm long, Figure 3e should read 2-3 μm min−1 and Figure 4a should read 40 μm.