NR4A1 and neoplasm: The here described elevated levels of the VEGF-receptors, Nur77, Ang2, and Tie2 in the tumor vascular compartment compared to the tumor compartment [16, 23], as well as the significantly higher level of PDGF-B, a molecule extensively produced by angiogenic tip cells on a sprouting tip [33], suggest a VEGF/Ang2-driven proangiogenic phenotype of the B16.F10 model employed.