Unsupervised hierarchical clustering of lung tumor and non-malignant miRNA expression profiles. Clustering of all 188 miRNA expression profiles revealed two distinct clusters, one comprised of non-malignant samples (teal), and the other comprised of mostly tumors (pink) (A). The clusters identified were associated with malignancy, as clusters 1 and 2 were significantly enriched for non-malignant and tumor profiles, respectively (Fisher’s Exact test p =2.2 × 10-16) Clustering of non-malignant tissues only (B) and tumors only (C) revealed three clusters. (D). Assessment of the distribution of CS, FS, and NS within the clusters identified in non-malignant samples revealed enrichment for CS and FS in clusters 1 and 2 compared to cluster 3 (Chi-square test p =5.0 × 10-4) (E). The same trend was observed in the clusters identified based on tumor profiles (Chi-square test p =0.023) (F).