Figure 2

Degree distribution of the whole human miRNA-mRNA target network. Panels (A) and (B) respectively illustrate the In- and Out- degree distributions of the random network, whichwas simulated with the same number of miRNA and mRNA nodes and miRNA-mRNA target pairs. The x-axis represents log-2 based degrees, and the y-axis indicates the log-2 based frequencies of nodes with corresponding degrees. The in-degree and out-degree distributions for the random network were symmetrical while the panels (C) and (D) show the power law distributions with slopes of -2.37 and -0.71 for the in-degree and out-degree distributions of the real network, respectively. The circle inside the small pane in panel (C) represents genes (34.41% of total genes) that were uniquely targeted by an individual miRNA.