Although FAK deletion was not apparent in endothelial cells isolated from pdgfrβcre+;fakfl/fl mice, since our in vivo results showed that endothelial cell proliferation was enhanced in tumours grown in these mice, we examined VEGF-receptor 2 (VEGFR2) levels and downstream ERK1/2 phosphorylation in endothelial cells isolated from pdgfrβcre-;fakfl/fl and pdgfrβcre+;fakfl/fl mice. This evidence concerns the gene PTK2 and neoplasm.