For each category of BC genes (A, C, HIV, and PI genes), we compute enrichment of GDC-central and non-GDC-central genes in each of the Gene Ontology (GO) terms [71] . We consider all GO terms belonging to each of the three GO categories: Hence, central genes appear to group by functions that are different than functions of non-central genes. Biological functions with the most significant enrichments that are present among all groups of central genes (but none of which is present among any of the groups of non-central genes) include many processes critical for normal cellular functioning, such as: regulation of cell cycle, , and pathogen-interacting (PI) genes). In all panels, the values of k where precision and recall cross (as illustrated in Figure 5 ) are used; k equals 3, 10, 12, and 6, for A, C, HIV, and PI genes, respectively, for each of the four centrality measures. doi:10.1371/journal.pone.0023016.g006 apoptosis, multicellular organism growth, telomere maintenance, innate immune response, regulation of cell differentiation, signal transduction, activity of many signaling pathway cascades (e.g., MAPK, I-kappaB kinase/NF-kappaB, EGFR, FGFR, IGFR, androgen receptor, nerve growth factor receptor, T cell receptor, toll-like receptor, etc.), phosphorylation, response to DNA damage, blood coagulation, regulation of cell proliferation, T cell activation and co-stimulation, response to tumor necrosis factor, response to drug, interspecies interaction between organisms etc.