FAP and glioblastoma: Since it has been shown that in some, but not all cell types, the FAP gene is a transcriptional target for TGFbeta signaling [23], we studied several cell types isolated from or serving as model systems for the complex glioblastoma microenvironment to assess whether TGFbeta participates in the upregulation of FAP gene expression in particular subpopulations of transformed and stromal cells typically present in glioblastomas.