Figure 3

Disease- and pathological condition-related nodes in the essential network. A. Bar charts of network diameters for five diseases, three pathological conditions, and nondisease gene-related PPIs (i.e., housekeeping and essential genes). B. Numbers of edges and nodes in the five disease- and three pathological conditions-related PPIs in log scale. In addition, the numbers of nodes and edges in the housekeeping and essential networks are also presented. C, D, E. Alteration of the diameter of the essential network by removing nodes. As a scale-free network, the essential network was robust against random errors (blue line in panel C), but was vulnerable to high-degree node attacks (red line in C). While an attack of pathological conditions showed random error-like effects on the essential network (cyan, black and violet lines in D), attacks on disease-related essential genes caused dramatic perturbations to the linkages within the essential network (green, pink and orange lines in E).