CCL2 and cancer: In this model, metastasis‐associated macrophages (MAMs) and their progenitor cells (MAMPCs) accumulate in the metastatic lungs via CCL2‐CCR2 signaling.17, 18 Since the accumulation of MAMs and MAMPCs promotes metastasis, these cells are regarded as attractive targets in anticancer therapy.17, 18, 19 Animals injected with E0771‐LG cancer cells formed metastatic tumours in their lungs after 2 weeks, as confirmed by whole‐body bioluminescence imaging (Figure S8).