In MDS, MDSCs are one of the sources of S100A8 and S100A9 in the bone marrow microenvironment; S100A8 and S100A9 secreted by MDSCs bind to the TLRs on the surface of HSCs, and initiate the innate immune responses described above [25,26]. The gene discussed is S100A9; the disease is myelodysplastic syndrome.