Fig. 2

Statistical patterns of organization in the human transcription factor network (Rodriguez-Caso et al. 2005). In a, we display the degree distribution P(k) associated with this network on a log–log scale. A heterogeneous distribution is observed, with a predominance of elements having one or two links but also with a few hubs (compare with Fig. 1). The statistics of network subgraphs shown in b reveal that they follow a decreasing exponential decay, with subgraphs ranked from the most frequent to the least