View of three modules of the E. coli network. The blue module corresponds to cell division and chaperones. The red module is related to RNA polymerase and the green module involves DNA metabolism. The size of the nodes indicates their absolute degree or number of connections. Conserved nodes in Buchnera are shown in darker colors, while conserved connections are shown in thick black lines. Connector hubs are completely conserved, whereas non-hub connectors are deleted in some instances.