Norbert Perrimon wants to understand how cells, tissues, and organs communicate during development. Working in Drosophila, Perrimon’s lab group uses techniques such as genome-wide RNAi and CRISPR screening and large-scale mass spectrometry to identify components of signaling networks and points of intersection, or “cross-talk nodes,” between signaling pathways that produce coherent responses. A more thorough understanding of these events can help elucidate how different tissues and cell types integrate within an organ, and how complex phenotypes arise in animals.