KDR and neoplasm: The metastasis phenotype of Flrt2iΔEC mice was in stark contrast to that of endothelial Vegfr2-knockout mice (Cdh5-BAC-CreERT2Vegfr2fl/fl, referred to hereafter as Vegfr2iΔEC mice); AXT cells transplanted into Vegfr2iΔEC mice showed increased metastasis to the liver, despite the decreased growth of primary tumors, likely due to the increase in hypoxia caused by excessive destruction of tumor vessels (Supplemental Figure 9).