FAP and central nervous system cancer: A considerable TGFbeta-1-mediated upregulation of FAP enzymatic activity was also observed in four out of five tested non-stem glioma cell cultures (Figure 4B, left part), while TGFbeta-1-treated glioma stem-like cell cultures showed either no change or negligible increase in their extremely low baseline FAP enzymatic activity (Figure 4B, right part).