GMNN and ovarian cancer: To address the difficulty of clearly separating cells in different cell cycle stages with FACS sorting using DAPI staining, and to show the generalisability of our approach, we transduced ovarian cancer PEO1-STOP cells with the FUCCI expression system facilitating accurate sorting of cells based on markers indicating different phases of the cell cycle including Geminin, expressed in S and G2 phase, and Cdt1, expressed in G1 and early S phase.