Expression value comparisons between siblings. The expression of all the genes shown are associated by the same sigma factor sigma70. Panels (A) and (B) compare the expression values of genes that originally appeared associated only by the same sigma factor in the global regulatory network. The genes rspD and rspM shown in (A), are nearly linear related, while glyW and asnT shown in (B) have a more complex relationship. After POBN optimization, ompF gene was disconnected from 8 of its 9 originally regulators in the global regulatory network. Panels (C) and (D) illustrate two examples of the association of ompF with genes under this same single sigma factor sigma70. Note that different but clear non-linear associations are observed between ompF and its siblings.