de Jong S et al. BMC Genomics 2010, 11:20 http://www.biomedcentral.com/1471-2164/11/20 Page 7 of 14 module (68 out of 76 genes are known) had significant overrepresentation of genes in the ‘Diseases and Disor- ders’ subcategory Dermatological diseases and condi- tions (6.6e-4 - 7.1e-3). Results for categories enriched by at least one module at the p < 10e-04 level are shown in the color-coded bar plot in Figure 4. The complete results from the Ingenuity analysis are provided in Addi- tional File 6. A visual representation of the network for the Red module is given in Figure 5, highlighting the strongest connections between hub genes and the invol- vement of the genes in different functional pathways. Discussion In this study, we applied systems biology methods to identify modules of co-expressed genes highlighting dif- ferences between the hippocampus and amygdala in two mouse inbred strains, A/J and C57BL/6J. Rather than generating a list of differentially expressed genes, this Figure 4 Color-coded bar plot depicting Ingenuity Pathway Analysis results. We used Ingenuity Pathways Analysis (Ingenuity® Systems, http://www.ingenuity.com) to study the ontology of genes in the Red, Pink and Magenta modules. Results for categories enriched by at least one module at the p < 10e-04 level are depicted in the color-coded bar plot.