CCR2 and melanoma: We found CCR2-RFP expression around melanoma cells only in mice that received BM cells from Ccr2RFP/+ (Supplemental Figure 14E, top row) mice, but not Ccr2RFP/RFP (Supplemental Figure 14E, lower panel) mice, confirming that knockin mutation of Ccr2RFP/RFP prevents egress of I-NCMs into the established metastatic colonies.