Figure 3

a, b: Degree distribution of the therapy network at level 2 (a) with degree exponent γ = 0.76 ± 0.10 and level 3 (b) with γ = 1.11 ± 0.14. c, d: Correlation between the node degree k and the betweenness centrality B _i (c) and the closeness centrality (d) in the drug network at level 2. The correlation coefficient r is indicated in figures. The P-value is below 2.2e-16 in all cases.