Cell rounding and cell–substratum adhesion are important for the revolving movement of the actin cluster. (A) Time-lapse images of HeLa cells expressing GFP-UtrCH and DsRed-histone H1 during interphase (top) and M phase (bottom) under the 3D condition. Images were taken every 1 min or 30 s, respectively. The pictures of interphase or M phase, at every 1 min or 2 min, respectively, are shown. Arrowheads indicate the actin cluster. Bar, 10 µm. (B) Spatiotemporal representation of GFP signals of A. (C) Confocal images of cross sections of living HeLa cells expressing GFP-UtrCH.