SOAT1 and neoplasm: A study on breast cancer revealed that miR-9 and miR-181a from tumour exosomes activated the JAK/STAT signal transduction pathway by targeting SOCS3 and PIAS3, respectively, thus promoting the expansion and infiltration of early-stage myeloid-derived suppressor cells in situ, inhibiting T-cell immunity, and promoting tumour growth and immune escape [193] (Fig. 4).