Known Yeast Cell Cycle Interactions. Schematic of known yeast cell cycle interactions between protein products of the twelve genes we studied (Table 1). An arrow indicates a positive interaction and a closed circle indicates a negative interaction. A dashed line indicates a protein-protein (e.g., phosphorylation, etc.) interaction and solid lines indicate direct transcriptional regulation. Genes are shown adjacent to each other when they are treated as a cluster in the KEGG pathway diagram (in the case of SBF and MBF the genes code for protein subunits). A connection inside a cluster indicates regulation of the whole cluster simultaneously. The interactions are located along an approximate time axis through the stages of the cell cycle (G1, S, G2).