The Notch pathway: democracy and aristocracy in the selection of cell fate.

Major advances in the past two years have increased our understanding of the molecular components of the Notch signal-transduction pathway in both invertebrates and vertebrates. Recent studies have begun to address the interaction of other signaling pathways with the Notch pathway. Of particular interest is the integration of signals from the Wingless pathway and from asymmetrically segregating determinants such as numb. Molecular models for Notch-mediated cell-fate selection within groups of developmentally equivalent cells are presented.