I was reading a recent paper (http://www.ncbi.nlm.nih.gov/pubmed/27127236) and am struggling with one of the figures. Specifically, Figure 1A states:
(A) GSEA demonstrates up- and down-regulated signaling pathways in MuSCs from 2-year-old mice, as compared with 3-month-old mice. This panel shows the results of our analysis of microarray data from the publicly available GEO data set (accession number GSE47177), using Kyoto encyclopedia of genes and genomes (KEGG) enrichment. Signaling pathways were ranked on the basis of normalized enrichment scores (NESs); positive and negative NESs indicate down- or up-regulation, respectively, in aged MuSCs. Specific pathways related to MuSC function are highlighted in red and blue. TGFβ, transforming growth factor–β
What does the horizontal scale represent? Is it simply some arbitrary unit? Is it some kind of measure of KEGG signaling pathway matching?
How would one go about generating such a figure? Perhaps that would best explain how to interpret this panel...