CSF1 and neoplasm: To investigate whether tumor EVs educate macrophages toward a pro-metastatic TAM phenotype, we treated bone marrow-derived macrophages (BMDMs) with tumor EVs for 48 h in the presence of macrophage colony stimulating factor (M-CSF), creating tumor EV-educated macrophages (TEMs) (Figure 1A, Figures S1 and S2; Appendix A).