Elevated TGF-β levels as detected in glioblastoma patients were also shown to affect the expression of NKG2DLs (104, 112): experimentally reduced TGF-β expression by glioma cells led to an increase of MICA, ULBP2, and ULBP4 transcripts and increased cell surface expression of MICA and ULBP2 as well as of a reduction of tumorigenicity in vivo (104, 112). This evidence concerns the gene TGFB1 and central nervous system cancer.