Fig. 1From: Convergent Evolutionary Paths in Biological and Technological NetworksCellular networks are heterogeneous. In a, we display the human transcription factor (TF) network (Rodriguez-Caso et al. 2005) where each node is a TF and links indicate the presence of protein–protein interactions. Different modules are indicated by means of different colors (see text). These modules are typically organized around hubs. Each TF is a protein that binds to DNA (an example is shown in b), and thus, the TF network would be a map of the cell hardware that “reads” the information stored in the DNA sequence (which would be the software)Back to article page