Development of a stromal activation-associated 51-gene signature in tumor epithelium. (A) Expression of 48 probe sets that were significantly up/downregulated in the stroma of subgroup G4 in 46 stromal samples. (B) Identify a principal component (SPC1) in stroma that represents collection group of 48 probe sets and measures differences of SPC1 score in stroma from different subgroups (n = 46). (C) Identify a principal component (EPC1) in tumor epithelium that represents the collection of stromal activation-associated genes (51 genes) and measures differences of EPC1 score in tumor epithelium from different subgroups (n = 46). Differences for each pair-wise comparison were assessed by Mann-Whitney U test. Boxes represent the 25% to 75% quartiles, lines in the boxes represent the median level, whiskers represent the non-outlier range, and circles represent the outliers.