Unsupervised hierarchical clustering and principal component analysis. (A) Visualization of group differences (ed12MC, ed12FC, ed12ME, ed12FE, ed17MC, ed17FC, ed17ME, ed17FE) for 204 peptides, using two-way clustering of the log2 ratio (Xclass-Xtot) between the group median value (Xclass) and the total median value for every peptide (Xtot). (B) One-way clustering of 38 identified peptides. Positive values are colored red, negative are green. (C) Principal component analysis using two components (C1, C2). The last letter(s) in the group definitions ed12/17XX stand for M = male, F = female, C = controls, E = ethinylestradiol exposed. # designates the peptide numbers in the data set.