Gene networks from DNA microarray data: centrality and lethality
  We construct a gene network based on expression data from DNA microarray experiments, by establishing a link between two genes whenever the Pearson's correlation coefficient between their expression profiles is higher than a certain cutoff. The resulting connectivity distribution is compatible with a power-law decay with exponent ~1, corrected by an exponential cutoff at large connectivity. The biological relevance of such network is demonstrated by showing that there is a strong statistical correlation between high connectivity number and lethality: in close analogy to what happens for protein interaction networks, essential genes are strongly overerpresented among the hubs of the network, that is the genes connected to many other genes. 
P. Provero