Figure 1.

The exhibition of results of HCL and PCA. Hierarchal clustering: the analysis was performed using the Euclidean distance and the average linkage algorithm; principal component analysis with scaling. (a) dendrogram plot: the astrocytomas tissue group and normal-tissue group were separated obviously in the top node; tumor node is composed of two branches, one is just WHO II grade, and another includes WHO III cluster and WHO IV cluster; (b) heatmap plot: each column represents the expression levels for all genes in a particular sample, whereas each row represents the relative expression of a particular gene across all samples. The expression level of any given gene in any given sample (relative to the mean expression level of that gene across all tissue samples) is reported along a color scale in which red represents transcriptional upregulation, green represents downregulation, and the color intensity indicates the magnitude of deviation from the mean; (c) the two main principal components 2D-plot; (d) the three main principal components 3D-plot. In Figures 1(c) and 1(d): different colors stand for different pathological stages, Green, blue, yellow, and red represent normal, II, III, and IV grade, respectively.