Single-cell RNA-seq integrative analysis in lung cancer metastasis. (A) UMAP projection of all the cells grouped by cell clusters (n = 7), studies, or sample origin sites. (B) UMAP projection of tumor cells grouped by different origin sites. (C) Pseudotime analysis of tumor cells. (D) Pseudotime distribution among the normal lung tissue (nLung), tumor lung tissue (tLung), metastatic lymph nodes (mLN), and metastatic brain (mBrain) groups. (E) Comparative analysis of differentially expressed genes in tumor cells. Functional pathway enrichment analysis of (F) mLN-specific differentially expressed genes and (G) mBrain-specific differentially expressed genes.