Table 1.

Almost all globally essential reactions in E. coli, S. cerevisiae and S. aureus are UP or UC. The p value represents the probability that the indicated overlap would arise in a null model as discussed in the text.

Organism	E. coli	S. cerevisiae	S. aureus
Total number of reactions	1176	1579	865
Number of globally essential reactions	164	127	196
Number of globally essential reactions that are UP or UC in the entire network	133 (p < 10-37)	86 (p < 10-12)	157 (p < 10-32)
Number of globally essential reactions that are UP or UC in the reduced network	156 (p < 10-62)	117 (p < 10-41)	182 (p < 10-58)