Mapping of differentially expressed genes into human pathways. Differentially expressed transcripts showing a +/- 2-fold change or greater were selected from the microarray data were analyzed using IPA software to identify potential homologous human pathways. From the 572 gene IDs of the differentially expressed gene set between R15 mature and old single neurons, 190 human homologs were identified. (A) Top 12 pathways from IPA analysis (B) Network 1, identified from IPA analysis, has 25 genes differentially expressed that are associated with cell signaling, cell morphology, and skeletal muscular system development. Node (gene) and edge (gene relationship) symbols are shown along with network diagram. Red shows genes that are upregulated and green indicates down regulation of the genes. Uncolored notes represent genes that were not identified in our data set as differentially expressed in our analysis, but relevant to this network.