 As a cell prepares to divide, its microtubules, arrange themselves into a spindle that permits its chromosomes to split into two bundles.These bundles become the nuclei of the daughter cells, Out-of-control cell replication is the underlying cause of cancer, developing drugs that interfere with microtubule activity offers one potential therapeutic approach.They can operate microtubule dynamics with a subsecond response time and control mitosis in living organisms with single-cell spatial precision.