Only during cell division. Our research is all about the mitotic spindle so, we study chromosome movement to the metaphase plate, the oscillations of the chromosomes once they align at the metaphase plate, and then, the subsequent separation of the sister chromatids during anaphase. Of course, once we start blocking the function of proteins, the chromosomes don't always move or align properly and that's how we draw conclusions as to how the proteins may actually function within the mitotic spindle apparatus. It's a difficult task, trying to characterize the functions of all the proteins, seeing as how there are thousands of proteins involved and some of them are very difficult to work with (believe me, I know this from experience *kicks Astrin*).