MCF7 cells carrying the NLS-mCerulean reporter were imaged over the course of 12 days. Time elapsed in each frame is demarcated by hhh:mm:ss. Initial cell division of target cell (labeled in blue) divides into two daughter cells (labeled in yellow and blue). Yellow daughter cell divides at ~t=62 hours into the movie. Blue daughter cell divides at ~t= 175 hours into the movie, demonstrating a 113 hour difference in sibling-sibling cell cycle time.