The Cluster of Excellence CellNetworks, centered on world-renowned Heidelberg University, unites more than 100 leading research groups from the faculties of Medicine, Bioscience and Natural Science, DKFZ, EMBL, MPI for Medical Research, HITS and the Central Institute for Mental Health, in one common objective: to explore complex networks within and beyond the cell, to describe functional interaction in unprecedented detail and truly understand how it all fits into place.