Significant upregulation of vegfaa expression was also observed in hemangiosarcomas that were isolated from adult zebrafish mutants that retained one wild-type allele of pten. Hemangiosarcomas are tumors that consist of endothelial cells and exhibit constitutive expression of Vegfr2 (kdrl) (Jinnin et al., 2008). This evidence concerns the gene KDR and angiosarcoma.