Enrichment of interactions between essential proteins in raw and high-confidence yeast PPI data sets.

All P<0.0001. aAverage number of interactions observed between essential proteins for 1000 simulations in which essential proteins were selected randomly from all proteins occurring in a network. In each simulation, the total number of selected proteins and their degree distribution were constrained to be identical to those of the actual essential proteins. bStandard deviation for simulations described above.