Figure 4

Distribution of expression level of cell type-specific genes in the small airway epithelium of healthy nonsmokers. Lists of genes specific to neuroendocrine cells, basal cells, secretory cells (including all mucins) and ciliated cells were used to assess the cumulative frequency distribution of expression levels for each category. The lists of cell type-specific genes are from the literature, including neuroendocrine genes [31], basal cells [30], secretory cells and ciliated cells [52]. Ordinate - cumulative frequency; abscissa - expression level (RPKM in 1/2 log₁₀ bins).