Figure 4. GO-tree analysis based on biological process. Arrow source, a GO term at a lower level; arrow target, a GO term at a higher level. Relation: is a, the downstream GO term is completely subordinate to the upstream GO term; part of, a part of the downstream GO term is subordinate to the upstream GO term; regulates, the downstream GO term can regulate the upstream GO term; positive regulates, the downstream GO term can regulate the upstream GO term positively; negative regulates, the downstream GO term can regulate the upstream GO term negatively.