FIG. 3.

Model for tumor-mediated suppression of IRF-8 during the production of G-MDSCs. Tumor-derived factors (TDFs) acting through STAT3, STAT5, or Id1 (for example) suppress IRF-8 transcription/expression during myeloid differentiation or at other cellular levels, which influence survival/persistence. This may occur in the bone marrow at the oligopotent granulocyte–monocyte progenitor (GMP) stage or the granulocytic progenitor (GP) stage, or in the periphery to drive expansion or enable persistence of circulating G-MDSCs (indicated by dashed red line). How potential loss of IRF-8 in monocytic progenitors (MPs) impacts monocyte production or M-MDSC accumulation in cancer requires further investigation.