Detail of a sub-network of the Cell Proliferation Network showing regulation and downstream effects of CDK2 kinase activity. Nodes in the Cell Proliferation Network are represented by orange rectangles (e.g. CCNE1 or kaof(CDK2) (kinase activity of CDK2)). Edges on the model (connections between nodes) are represented as lines. Non-causal edges (e.g. the relationship between CDK2 and the kaof(CDK2)) are shown in light grey lines. Causal edges are represented by dark black lines, with edges ending in arrowheads designating positive relationships (e.g. increases or activates) and edges ending in a ball designating negative relationships (e.g. decreases or inhibits). Specific phosphorylation sites are designated with the P@X representation, where X is a specific amino acid residue or residue class. For example, the kinase activity of CDK2 phosphorylates RB1 at serine (S) residue 373. In the sub-network detail, the "kaof" prefix refers to the kinase activity of a node, while the "taof" prefix refers to the transcriptional activity of a node. Figure 4 contains a key relating the prefixes shown in the sub-network detail to their biological meaning/interpretation.