Effect of RNA degradation on comparability between patients. (A) Two-dimensional PCA plot of genome-wide expression profiles showing principal components 1 and 2. The first axis (PC1) accounts for 33% of the overall variance of the data, the second axis accounts for 29% (PC2). The colors blue (P159), red (P160) and green (P162) refer to the different patients. The degradation levels are represented by the following symbols: C (0:00 h), 1 (1:45 h), 2 (2:30 h) and 3 (3:15 h). (B) shows pairwise correlations between all samples of patients. The cells in the visualization are colored by Pearson's correlation coefficient values with deeper colors indicating higher positive (blue) correlations. The heatmap is flanked by clustering dendrograms showing the similarity between samples in a hierarchical approach.