Signaling pathways (SPs) that we analyze include the human: MAP kinase interactome [68] , cancer and immune pathways from NetPath [69] , and all human signaling pathways from KEGG [65] . The data are downloaded in November 2010. In the PPI network, there are 2,253 SP genes, 911 of which are also BC genes. Given that there is a total of 2,101 BC genes in the network, the total number of BC and SP genes together is 2253z2101{911~3443.