Fig. 1.

Quality control for data analysis. The array expression data (from all 41,345 probes) of each sample are projected to the first two components of PCA, P1 and P2 in a, showing the separation of 6 samples into three groups. This separation is also shown in the 6 × 6 matrix of the correlation coefficients between samples (b). The plot in (c) shows the selection criteria for significant fold change in individual gene expression: the absolute fold change has to be bigger than 2^0.5 (red and blue dots), and the p-value has to be smaller than 0.05. For functional analysis, the selected genes are ranked by p-value and are further selected by Benjamini-Hocheberg method to limit FDR (d).