FIGURE 7.

Reference Model for Segment Polarity Network. Diagram of the interactions in Albert and Othmer’s model of the segment polarity network (Albert and Othmer, 2003). Green edges indicate activating interactions. Red are inhibiting. Lower case ovals indicate genes and upper case indicate proteins. The dotted border indicates the cell membrane, with membrane proteins straddling the border. On the right is the adjacent cell, with several interactions spanning between cells. Albert and Othmer’s model has four cells with the same interactions inside each cell. Interactions between cells are symmetric, though only one direction is shown in the diagram to maintain clarity.