Population doubling time and cell cycle duration of Fucci2 mES cells. Fucci2 mES cells were plated on E-cad-Fc at a density of 1 × 105 cells in 35 mm dish (A). Cell numbers were counted at each day (2 to 3 replicates) in two independent experiments using a Trypan blue exclusion assay. Data are mean ± SD, n = 3. Cell cycle duration of individual Fucci2 cells was measured by time lapse video microscopy (LCV110-Olympus). Histogram represents the duration of 29 individual cells for 72 hr (B).