Here, we show that exosomes released from non-metastatic melanoma cells (ExoNM) are taken up by CD11b+ myeloid cells in the bone marrow (BM) and cause a Nr4a1-driven expansion of Ly6Clow monocytes, which display elevated levels of integrin-β2 (ITGB2) and CX3CR1 (fractalkine receptor), and Nr4a1 orphan nuclear receptor, which together define PMo38,39. The gene discussed is NR4A1; the disease is melanoma.