Figure 4

Gene regulatory network associated with proliferation in primary breast cancer. Gene Regulatory Network (GRN) inferred from differential gene expression profiling in 1191 whole genome expression experiments for biopsy samples from breast cancer patients/controls (Baca-López et al. 2012). Panel A depicts the associated GRN. The relative importance of highly connected genes is not evident. Panel B depicts the same network, nodes are size-coded and color-coded according with their connectivity degree (big red nodes correspond with highly connected genes, whereas small green nodes are lowly connected genes). Some genes apparently stand-out as relevant, however the intricate network structure does not permit to tell indirect connections from direct ones, also a number of medium-level connected nodes add complexity to the analysis. In panel C we can see the connectivity degree distribution: no definite trend is evident -e.g. a power law, a stretched exponential, etc.- but the distribution remains somehow homogeneous for the range between a few connections and more than a hundred connections. In panel D we can see how the average clustering coefficient almost follow a power-law (R² = 0.85 for the power-law fit) indicating that there may be a hierarchy related with how nodes associate. This could be an indication that a number of not-so-strong interactions are present. Panel E presents the short path length distribution that in this case is a bimodal (with maxima at distances of 2 and 4 links) with a short tail.