Figure 4. IQGAP1 is a key node within the small GTPase network. To construct a small GTPase network, 144 out of the 162 known small GTPases were mapped onto literature-based protein-protein interaction (PPI) databases (18 small GTPases not found in the databases) and their known direct binding partners were selected. Each node represents a protein and each edge represents a reported interaction between 2 proteins. Nodes of this network were automatically organized using an algorithm that clusters nodes as a function of their connectivity. Small GTPases are highlighted in Red and IQGAP1 in yellow. Node size is proportional to the network topological parameter Stress. The stress of a node n is the number of shortest paths passing through n. A node has a high stress if it is traversed by a high number of shortest paths. Some nodes of interest were manually labeled.