Jiefu Li investigates the operating principles and mechanisms of cell-surface signaling in the nervous and vascular systems. Intercellular adhesion and communication, which are the foundation of multicellularity, take place at the cellular interface and rely on cell-surface molecules. Cell-surface signaling thus controls nearly every aspect of the development, physiology, pathogenesis, and evolution of multicellular organisms. Li and his team innovate new methods and tools to analyze cell-surface signaling in vivo across systems, cellular, and molecular scales.