Figure 2
From: Notch signaling, the segmentation clock, and the patterning of vertebrate somites
Lateral inhibition in differentiation. Two neighboring cells each express both the Notch receptor and its ligand, Delta, but the cell on the left expresses Delta more strongly, so that the Hes/her gene is activated in the neighboring cell (on the right), and its product, an inhibitory transcriptional regulator, acts in this cell to block expression both of Delta and of genes for differentiation. Consequently, in the left-hand cell Notch is not activated, the Hes/her gene is not transcribed, Delta expression is maintained, and genes specifying differentiation are expressed.