ELISA analysis of PlGF and VEGF-A secretion in culture supernatants collected from the different GBM cell lines revealed that: a) PlGF was produced by most of the cell lines tested and was nearly undetectable in T98G cells (Fig. 1b, upper panel), and b) all cell lines secreted substantial amounts of VEGF-A (Fig. 1b, lower panel). This evidence concerns the gene PGF and glioblastoma.