(G) Gene set enrichment analysis (GSEA) and gene ontology (GO) analysis of genes differentially expressed between young and old dermal fibroblasts. Categoriesderived from GO analysis using David 6.8 are marked with ‘‘(GO),’’ categories derived from GSEA are marked with ‘‘(GSEA).’’ For the GSEA categories the FDR isindicated; for the GO categories, the p value is indicated.(H) Unsupervised clustering of young and old fibroblast samples based on gene ontology signatures. The intensity of the colors represents the expressionintensity from blue (low expression) to red (high expression).