MUC5AC-core genes assessed by RNA-Seq analysis in healthy smokers and healthy nonsmokers. Shown is a hierarchical cluster analysis of RNA-Seq data of expression of the MUC5AC-associated core genes from 5 healthy nonsmokers and 6 healthy smokers. Smoking status was represented by different colors (nonsmoker, blue; smoker, brown). In the heat map, gene expression above the average is represented in red, below average in blue, and average in white. The color schemes represent the relative expression level across each row (each gene). Dendrogram color denotes there are two different groups independent of smoking status. The expression level (RPKM) of MUC5AC is shown under the label of each individual (NS = nonsmoker; S = smoker).