Credit: Salk Institute
In early-stage cell nuclei (blue), developmental genes (green) must be turned on for the cell to develop. When the two cellular processes, Wnt and Activin, work together (upper left), genes are activated to a much greater degree than when neither process is active (upper right). When just a single pathway is active (Wnt, lower left, Activin, lower right), only a few genes are turned on.