VEGF has been found to potently activate the expression and functional activity of all three NR4A members, and in NR4A1−/− knockout mice, tumor growth, angiogenesis, and microvessel permeability are almost completely inhibited, further purporting a critical mode for these orphan receptors in tumorigenesis (Zeng et al., 2006). This evidence concerns the gene VEGFA and neoplasm.