Figure 1.

Variation in Fucci Fluorescence Colors by Cell-Cycle Phases. Nuclei of resting G₁ hepatocytes predominantly express the red Cdt1 gene and thus appear red. As G₁ cells transition into the S phase, their nuclei contain both red Cdt1 and green Geminin, giving the nuclei a yellow/orange appearance. When hepatocytes fully enter the S, G₂, and M phases, their nuclei express only green Geminin. The cell cycle is repeated as the green hepatocytes divide into 2 daughter red G₁ cells. Some G₁ cells may enter in and out of the G₀ phase of the cell cycle.