Automated Cell Cycle Analysis Figure 3. TSA detects small increases in mitotic duration when the spindle assembly checkpoint is activated by nocodazole. (a) HeLa H2B-GFP cells were imaged every 12 min for 48 hours after treatment with DMSO. Mitotic events from one movie, for nuclei that were successfully tracked, were measured by TSA (tracked successfully) and duration of these events was manually determined and both measurements were compared. Mitotic duration was also manually determined for cells that were not tracked successfully. Such cells were either not present in the imaging frame at all time throughout the movie or their trace showed potential errors of segmentation or tracking and were as a result excluded by PLoS ONE | www.plosone.org 5 September 2011 | Volume 6 | Issue 9 | e25511