Double IF staining for FAP and TGF-β1 in the GBM models showed that about 10% of FAP+ cells also stained for TGFβ1, while ~ 30% (GL261) and ~ 75% (005) of TGF-β1+ cells were FAP+ (Fig. 4e). This evidence concerns the gene TGFB1 and glioblastoma.