Single, non-dividing cell from S phase synchronization experiment shows attenuated pHi dynamics over a 24-hour period. Video of a non-dividing cell over 24 h after release from a double thymidine block, compiled from a single Z-plane captured every 20 min. Arrows appear to show cell of interest at the beginning and end of video, scale bar: 20 μm. Ratiometric display of pHluorin/mCherry fluorescence ratios. Video is the same cell as Fig. 5D and ratiometric scale is identical.