S100A9 and neoplasm: Mø_c5-Mø_c7 showed a strong donor phenotype and were defined as monocytic myeloid-derived suppressor cells (M-MDSCs, 8.78%, 8.16%, and 7.95%, respectively), characterized by the high expression of S100A12, S100A9, and S100A818 (Supplementary Fig. S2g), as well as CCR2, which could facilitate their trafficking to tumor site19.