S100A9 and nonpapillary renal cell carcinoma: Within the ccRCC BM microenvironment, we identified 6 myeloid subclusters (Fig. 2A and Additional file 2: Fig. S2A): classical monocytes (Mono-1/Mono-2: S100A8, S100A9, and CD14), non-classical monocytes (Mono-3: lacked CD14 expression but expressed FCGR3A (CD16)), monocyte progenitor cells (expressed high levels of MPO and MKI67), dendritic cells (DCs, expressed CD1C and FCER1A) (Additional file 2: Fig. S2B,C).