In line with the in vivo data herewith obtained with fibrosarcoma PTX3 transfectants (see above) and previous observations on different FGF-dependent tumor types grafted in TgN(Tie2-hPTX3) mice (17, 24), endothelial expression and stroma accumulation of PTX3 significantly impaired the growth of fibrosarcoma MC17-51 tumor grafts in these animals. This evidence concerns the gene PTX3 and fibrosarcoma.