EGFR Contact Map. An example contact map from the EGFR family. The model contains five distinct types of molecules (shown as grey aggregates), each comprised of one or more components (yellow and purple rectangles), which can have one or more states (green rectangles). Each edge represents a possible binding interaction to a component (possibly in a given state), specified by one or more rules. Components shown in purple have states that are modified by the action of one or more rules. The rule-based model represented by this contact map generates a reaction network with 356 species and 3,749 reactions.