Figure 4.

Enrichment of differentially expressed bronchial epithelial genes among smoking-induced genes in the buccal mucosa or nasal epithelium. Results from gene set enrichment analysis (GSEA) shows that 361 genes induced in bronchial epithelial cells from smokers are significantly skewed toward being among the genes most induced in buccal (A) or nasal (B) epithelial samples in response to smoking (p < 0.001). There are 74 genes that comprise the buccal "leading edge subset" and 120 genes that comprise the nasal "leading edge subset". These two analyses suggest that genes induced by smoking in the bronchus show a similar pattern of differential expression in buccal and nasal epithelium.