A seminal issue in better understanding how cells respond to a variety of physiological cues is to elucidate how signaling cascades, and more generally biochemical networks, work and how they interact with one another. This special thematic issue of Molecular BioSystems, Monitoring and Manipulating Signaling Networks, provides a flavor of the many exciting advances being made along this long road. 

In the spirit of the mission of this journal, most of the articles were chosen to reflect common themes in systems biology, but we've made some idiosyncratic choices in order to drive home the message that chemists have a great deal to contribute to this emerging field. 

The issue is introduced by Professor Tom Kodadek from University of Texas Southwestern Medical Center in Dallas and Professor Steve Michnick from the University of Montreal (Chair and member respectively of the Molecular BioSystems Editorial Board).