GFAP and brain neoplasm: We identified commonly differentially expressed genes (106 up-; 379 downregulated in BCBM, Supplementary Data 6) enriched for pathways associated with the brain tumor microenvironment (GSEA; FDR < 0.25; NES ± 1.0), including GFAP, glial fibrillary acidic protein (a marker of reactive astrocytes), gene targets of NR2E1 (TLX), nuclear receptor subfamily 2 group E member 1(encoded protein regulates adult neural stem cell proliferation), and PTPRC, protein tyrosine phosphatase receptor C (signaling molecules that regulate multiple cellular processes16–18) (Fig. 2b and Supplementary Data 7).