The formation of the mitotic spindle during cell division requires the assembly of microtubules to form a bipolar array that ultimately results in chromosomal segregation. Mechanisms that guide this process are difficult to visualize, but several lines of evidence suggest that chromatin can guide microtubule assembly from a distance. In the September 30
Carzo-Salas and Karsenti used a novel assay system whereby chromatin beads—artificial chromatin aggregates lacking kinetochores—were mixed with human centrosomes in