Figure 5. The levels and correlations of the 62 significant features in smokers and non-smokers.

The log-transformed normalized intensities of the 62 features in the 9 samples were shown in the heat map. Obviously, 43 features were elevated in heavy smokers when compared to non-smokers while 19 features were reduced in the former. The correlations of the 62 features were shown by the Hierarchical clustering dendrogram. H1-H4: heavy smokers; N1-N5: non-smokers.