NR4A1 and neoplasm: We found that host genetic deletion of Nur77 in mouse markedly promoted tumor metastasis as revealed by increased macroscopically-visible metastases in the livers and lungs of the Nur77-/- mice 4 weeks after inoculation of B16 cells (Fig 1A and 1B) and developed more liver and lung micrometastases (Fig 1C and 1D) compared with Nur77+/+ mice.