In female mice, the pathway terms from KEGG mainly include pathways in cancer, proteasome, Huntington's disease and Amyotrophic lateral sclerosis (ALS). The genes expression of these pathways synchronously decreased in adrenal glands (AG), muscle (MU) and cerebellum (CE) from 1 to 6 months, as well as in gonads (GO) and muscle (MU) from 6 to 16 months. In contrast, asynchronous expression of genes from above pathways occurred from 16 to 24 months in liver (LI) and thymus (TH) (Table S2). The same situation also dramatically appeared in those terms from other databases resource such as ‘ubl conjugation’, ‘acetylation’ and ‘mitochondrion’ etc. in SP_PIR_Keywords (Table S2). In male mice, some cancer-related pathways such as Wnt signaling pathway were enriched by genes with asynchronous expression from 6 to 16 months in adrenal glands (AG) and gonads (GO) (Table S3). Besides, pathways enriched for asynchronously expressed genes occurring in middle or late life also had a distinct characteristic. Many were involved in repairing damaged DNA including base-excision repair (BER), DNA repair, synthesis and replication pathway, as well as degrading unneeded or damaged proteins such as ubl conjugation. Genes in these pathways presented asynchronous expression from 6 to 16 months in AG and GO. The similar situation also occurred in terms related to DNA/protein modification like ‘acetylation’, ‘phosphorylation’ etc. (Table S3).
http://plosone.org/article/info:doi/10.1371/journal.pone.0024076#article1.body1.sec2.sec3.p3

In female mice, many functional terms were implicated in DNA/protein modification and repair mainly including phosphoprotein (phosphorylation), acetylation, chromatin modification (GO:0016568), transferase, ER-associated degradation (ERAD) pathway, response to DNA damage stimulus (GO:0006974) and mismatch repair (GO:0006298) etc.. The majority of genes in these categories synchronously decreased expression from 1 to 6 months between adrenal glands (AG) and muscle (MU). In contrast, the minority of related genes synchronously increased expression from 16 to 24 months between cerebellum (CE) and muscle (MU) (new table S2). Besides, we also observed the part of genes in above terms showed asynchronous expression from 1 to 6 months between muscle (MU) and thymus (TH), muscle (MU) and hippocampus (HI), as well as glands (AG) and gonads (GO) (new table S2). In male mice, functional terms mainly were involved in phosphoprotein (phosphorylation) and ubl conjugation, genes in which synchronously decreased expression from 1 to 6 months in adrenal glands (AG), eye (EY), spleen (SP) and kidney (KI). In contrast, related genes in phosphoprotein (phosphorylation) asynchronously expressed in hippocampus (HI), spleen (SP) and kidney (KI) (new Table S3).