S100A9 and neoplasm: RNAseq analysis of 4T1 mouse tumors (TNBC) also showed that treatment with doxorubicin/GTN combination significantly decreases the expression of genes associated with MDSCs such as s100a9 (a member of the S100 family of inflammatory mediators that serves as an autocrine feedback loop that sustains accumulation and activity of MDSC) [25] and cxcr2, a chemokine receptor involved in recruitment of MDSCs to the tumor [26] (Figure 3C; Supplementary Figure S3).