S100A9 and myelodysplastic syndrome: Another study further identified S100A9 to act on myeloid-derived suppressor cells (an innate immune cell type with immunosuppressive potential enriched in the BM of MDS patients) and to upregulate secretion of suppressive factors (e.g., TGF-β and IL-10), thereby indirectly facilitating the expansion of the malignant clone (61).