Spindly (green) is enriched on kinetochores (red) that are not yet aligned on the metaphase plate.

Dynein has finally found a partner with direction. On page 1005, Griffis et al. identify a cofactor for the motor that seems to bring it to kinetochores and only kinetochores.

With everything it has to do in the cell, dynein has many places to be. During mitosis, dynein is needed at kinetochores, where it eventually drags spindle assembly checkpoint proteins off attached chromosomes so that anaphase can begin.

Plenty of cofactors that target the motor to its various locales have been identified, including dynactin and Lis1. But, like the motor, these partners have more destinations in mind for dynein than just kinetochores.

Not so for Spindly, a fly protein that Griffis et al. found in a high-throughput RNAi screen. This protein, and its human counterpart, was required to target dynein to kinetochores at the onset of mitosis. Without Spindly, cells were stuck in metaphase with dynein-free, checkpoint protein–laden kinetochores. All other assayed dynein functions, however, were left intact.

During interphase, Spindly was found at microtubule plus ends, where it somehow helped control cell shape, apparently without dynein's help. The authors are now tracking down how the loss of this protein in interphase creates the spindly cell shape that inspired its name.