NR4A1 and neoplasm: Intravascular adoptive transfer of sorted Ly6Clo monocytes into Nr4a1‐deficient mice that lack Ly6Clo monocytes reduces tumor metastasis by nearly 4‐fold in an experimental model of melanoma metastasis to the lung.3 Conversely, adoptive transfer of Ly6Chi monocytes nearly doubles tumor metastasis, consistent with their protumoral functions.