Figure 1: Multidimensional scaling plot summarizing gene expression differences between smokers and non-smokers. Each point represents an individual sample, and the distance between two points reflects the overall similarity in expression of the selected set of genes in those two samples. A) Separation of smokers and non-smokers according to 300 genes differentially expressed between all smokers and non-smokers, irrespective of their sex. The points are colored as red (male non-smoker), pink (female non-smoker), green (male smoker) and cyan (female smoker). B) Separation of male smokers (red) and non-smokers (green) using a set of 175 genes differentially expressed in male smokers and non-smokers. C) Separation of female smokers (red) and non-smokers (green) using a set of 247 genes differentially expressed in female smokers and non-smokers.