Fig. 2.

Proteomic analysis identifies 100 proteins that are significantly regulated at any time point. A, up- and down-regulated proteins were divided in three age groups: early-aged (40 to 50 weeks), middle-aged (60 to 80 weeks), and old-aged (90 to 100 weeks). B, all differentially expressed proteins were categorized in 17 functional synaptic protein groups as previously defined (20, 27). Only protein groups indicated in black print were significantly enriched in the corresponding age group (Fisher's exact test; p < 0.05; see also Table I). C, individual protein expression profiles of significantly enriched functional protein groups. Red indicates proteins that are up-regulated; blue indicates proteins that are down-regulated.