NR4A1 and neoplasm: To determine the specific role of CCR2 in the migration of I-NCMs into tumor colonies and overcome the inability of CMs to exit the bone marrow in Ccr2RFP/RFP mice, we reconstituted Nr4a1–/– Nod2–/– mice with established pulmonary B16F10-GFP metastasis with bone marrow from Ccr2RFP/RFP or Ccr2RFP/+ mice (Figure 5I and Supplemental Figure 14, A and D) and treated these mice with MDP.