Fig. 3
Protein-protein interaction networks of differentially expressed genes in metastatic breast cancer. A Protein-protein interaction (PPI) among 193 differentially over-expressed genes was examined to analyze the functional protein association network in metastatic breast cancer using STRING, an online tool. In total, 192 nodes (disconnected nodes are hidden) and 407 edges are presented. PPI enrichment P value is 1.11 × 10−16, which implies this network has significantly more interactions than a network with a randomly chosen set of proteins. B Protein-protein interaction (PPI) among 144 differentially under-expressed genes was examined to analyze the functional protein association network in metastatic breast cancer using STRING. In total, 143 nodes (disconnected nodes are hidden) and 190 edges are presented. PPI enrichment P value is 6.99 × 10−14, which implies this network has significantly more interactions than a network with a randomly chosen set of proteins. Circles and lines in A and B indicate genes and interactions, respectively. The line colors indicate the types of interaction evidence.