Unsupervised clustering using gene expression of CXCR2 and its ligands (CXCL6, IL8, CXCL2, CXCL1, CXCL3, PPBP [CXCL7], and CXCL5) in (A) 52 NSCLC cell lines and (B) 442 lung adenocarcinomas. For Gene Set Enrichment Analysis, genes were preranked according to the fold-change observed between samples with the CXCR2/CXCR2 ligands cluster and the remaining samples in both lung adenocarcinomas (C, D) and cell lines (E, F); representative gene sets enriched with a P-value and a false discovery rate <0.0001 are shown for lung adenocarcinomas (C, D) and NSCLC cell lines (E, F).