MPO and breast cancer: Consistent with previous reports that ADRB3 is highly upregulated on myeloid-derived cells [30], the MPE smears of BC patients (n = 8) shows high expression ADRB3 in cytoplasm, nucleoplasm and nucleolus of DTCs that surrounded by ADRB3+ MPO+ myeloid cell (Fig. 2A), indicating adhesive ADRB3+ IMCs provide a protective effect on activated DTCs survival.