A state of competition is imposed upon a cluster of cells. Perhaps the single cell, seemingly selected at random, is the one with the highest density of ligand. However, very little is left to chance. Three other proteins are involved in fate determination of the selected cell. The selected cell proceeds along a neural differentiation pathway, synthesizing higher levels of the proneural proteins, Achaete and Scute .
Lateral inhibition is one of the major themes of development.
The process of lateral inhibition and cell selection is repeated hundreds of times in Drosophila, with differentiation that takes place in nearly every kind of tissue. For example, Notch is required to limit the number of neural precursors , limit the number of muscle precursors, limit the growth of Malpighian tubules , and regulate the growth of the ovary . Notch also functions as receptor for both Serrate and Delta in organizing the dorsal-ventral boundary of the wing . Two extreme models can be envisioned for lateral inhibition. The first implicates the Notch pathway in the choice of a single precursor via a negative feedback loop.