Figure 2.

Analysis of the essentiality of hubs and composite hubs. (a) Comparison of the percentages of essential genes in hubs and non-hubs in different networks. P values measure the significance of differences between the percentages for hubs and non-hubs. (b) Comparison of the percentages of essential genes in non-hubs, hubs and composite hubs. In this figure, we excluded all composite hubs when calculating the percentage for hubs. Due to the limited number of tri-hubs, we combined them with bi-hubs. P values measure the significance of the differences between neighboring bars. Met, the metabolic network; Int, the interaction network; Exp, the co-expression network; and Reg, the regulatory network (in Figures 2 and 3, we only consider the regulator population in the regulatory network).