Interestingly, the switch in the expression levels of FGF1 and FGF2 (downregulated and upregulated in low-responder cells, respectively) as well as the upregulation of one member of the PDGF family (i.e. PDGFD) might be potentially driving the tumor progression in these GBM low-responder cells. This evidence concerns the gene PDGFD and neoplasm.