Breast cancer-derived exosomes carrying miR-9 and miR-181a contribute to the expansion of myeloid-derived suppressor cells (MDSCs) by downregulating suppressor of cytokine signaling 3 (SOCS3) and protein inhibitor of activated signal transducer and activator of transcription 3 (STAT3) (PIAS3), respectively (15). This evidence concerns the gene SOCS3 and breast cancer.