Protecting the ends

Increased microtubule dynamics during mitosis allows for the construction of a spindle, but may make the cytoskeleton vulnerable to the type of defects noted by Rogers et al. on page 873. They find that depletion of a fly microtubule- associated protein (MAP) called EB1 leads to problems in spindle construction, positioning, and functioning, probably because of a failure to counteract microtubule-destabilizing factors.

The product of the budding yeast homologue of EB1, called Bim1p, has been identified as a plus-end microtubule-binding protein necessary for positioning the spindle and promoting microtubule dynamics. Rogers et al. looked first in fly tissue culture cells that were grown so they flattened to double their normal diameter. This allowed the authors to visualize individual microtubules in vivo and confirm that microtubule dynamics are suppressed upon loss of EB1. This probably reflects the...