Fig. 3

Clustering of 120 subjects based on blood expression profiles of 25 genes which were significantly different by ±1.5 fold between SMK and either MSC or NTC subjects. a Hierarchical clustering and heatmap representation of expression values for genes (rows) across 120 subjects (columns), where low expression is denoted by green and high expression by red. The expression of each gene was normalized across all samples. Subjects were categorized into SMK (blue), MSC (red), and NTC (green). b Principal Component Analysis. Subjects were projected according to the first three principal components, which accounted for 35.7% (PC1), 10.0% (PC2) and 6.9% (PC3) of the gene expression variance. Subjects were categorized into SMK (blue squares), MSC (red spheres), and NTC (green triangles). The centroid of each group is depicted by a larger symbol with lines radiating to all of the subjects in that group