In order to investigate if the lack of an additional anti-tumour effect of anti-PlGF could be related to the expression level of PlGF and/or VEGFR-1 in the tumour cells, we performed qPCR for PlGF and VEGFR-1 in a small subset of the xenograft tumours and compared the expression to a panel of 13 GBM patients. The gene discussed is FLT1; the disease is glioblastoma.