Species equivalence classes in the site-specific logical EGF insulin model. The basal activities for insulin and EGF have been undefined, all other basal activities set to the value 1. Thus, for each of the ligand combinations (i.e. EGF and insulin absent, EGF and insulin present, either of them present) all species contained in one equivalence class have the same value in the corresponding logical steady state. Three different equivalence classes can be found for this particular input scenario: Yellow nodes indicate insulin-specific parts of the network (i.e. L-nodes that are on if insulin is present, off if insulin is absent); blue L-nodes indicate EGF-specific parts, and green L-nodes are influenced by insulin as well as EGF. White L-nodes are not contained in any equivalence class. The computation of equivalence classes has been performed in CellNetAnalyzer. The results have been re-imported and visualized in ProMoT.