The extra domain-B (ED-B)–containing fibronectin isoform (B-FN) is a marker of angiogenesis 1–2 that can be employed to selectively target the tumor vasculature using a human recombinant antibody specific for B-FN, L19 (scFv), both in experimental animal models and in cancer patients 3–4. This evidence concerns the gene FN1 and cancer.