Fig. 2

PPI network analysis of genes containing germline SNPs. a PPI network of germline SNP-containing genes of the five probands. Each node represents a gene containing a germline SNP, and each edge represents a PPI recorded in STRING-DB. Main graphs (the largest interconnected subgraphs) are colored in orange. b PPI network of germline SNP-containing genes of the three healthy controls. Main graphs are colored in orange. c Numbers of germline SNP-containing genes and genes in the main graphs. d Shortest path distribution in the main graphs. e Characteristic path length and average number of neighbors in the main graphs. f Node degree distribution of the main graphs of the five probands. Red lines are fits according to the power law. g The number of nodes in the main graph versus the percentage of nodes in the main graph over the total nodes. The five probands are colored in red. The five patients from independent high-incidence (HI) families are colored in pink. The three healthy individuals from high-incidence (HI) families are colored in cyan; the one who was diagnosed with lung cancer during this study, is shown with a star. Three patients with sporadic lung cancer are shown in orange circles. Three healthy controls are shown with blue crosses