Cytosolic Ca2+regulates the progression of MSCs through prophase. (A) Representative images of MSCs in prophase, metaphase, anaphase, and telophase. The confocal immunofluorescent images were obtained after staining with anti-phospho-histone-3 (green) and Hoechst dye (blue) to label the nucleus. Scale bar = 20 μm. (B) Mitotic MSCs were identified by phospho-histone-3 labeling and measured 48 hours after transduction with the indicated adenoviral constructs. Approximately 10 random fields were analyzed by using an Olympus IX70 inverted epi-fluorescent microscope to determine the average number of cells in the samples (61 to 70 cells were analyzed in each experimental group). The mitotic index increased to 61% ± 2% in cells in which cytosolic Ca2+ was buffered (*P < 0.001). In addition, 49.9% of the mitotic cells were in prophase.