Using the biological process ontology developed by the Gene Ontology Consortium, we calculated GO similarity scores. We then calculated gene/TF scores using the approach described in From Gene-Gene Scores to Gene-TF Scores Section. Fig. 7 shows the probability distributions for the training (gene/TF interactions in the preliminary TRN) and complete (all possible gene/TF interactions) sets. The significant variation between the training and random sets provides evidence that the likelihood for a gene pair to be regulated in the same manner increases with the similarity of their GO description. A comparison of Fig. 7 and Fig. 2 of Wu et al. (2005) shows that our approach is more successful in distinguishing the training and random sets (Note that [20] included pathway data in their training set whereas we only used the E. coli TRN).