Figure 2. Pathway analysis of the unfolded protein response mRNA transcripts post-exercise. The unfolded protein response (UPR) in skeletal muscle volcano plots of mRNA expressed as a log fold change from baseline to 18h post-exercise in young (A) and older (B) adults. The x-axis represents the log fold change, while y-axis represents the –log FDR-value for each gene. Dotted vertical lines represent the threshold for statistical significance (FDR < 0.05, −log [FDR value] > 1.303). Gene set enrichment analysis (GSEA) was performed using Broad’s GSEA software for 72 genes related to UPR pathway and revealed a significantly greater upregulation of the UPR pathway between rest and 18h post-exercise in young (C) compared to older (D) adults (FDR < 0.05 and an absolute log2 fold change ≥ 0.5). (E) UPR up- and down-regulated mRNAs significantly altered (FDR < 0.05 and an absolute fold change of ≥ 1.2) between baseline and 18h post-exercise in young and older adults, sorted by the log2 fold change. NS = not significantly altered.