2.4. Gene ontology and pathway analysis

To identify significantly represented biological themes and functional groups among the differentially expressed genes, gene ontology (GO) and pathway analyses were performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID) v6.8 program (http://david.abcc.ncifcrf.gov). The orthologs of human gene were used for analysis as described previously to increase the hit count (Nagasawa et al. 2013). The GO analysis was used to identify enriched biological themes using GO terms defined and provided by the Gene Ontology Consortium (http://www.geneontology.org). The ‘biological process’ subontology of GO (GO:BP) refers to a biological objective to which the gene contributes and is widely used to evaluate sets of relationships between genes. The pathway analysis was used to identify candidate gene involved in pathways from the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database (http://www.genome.jp/kegg/pathway.html).