Previous reports showed that miR-181a in EV promotes the development of early-stage myeloid-derived suppressor cells by interfering with protein inhibitor of activated STAT3 (PIAS3) [39], which targets mixed-lineage leukemia 3 (MLL3), and therefore induced angiogenesis and tumor growth in papillary thyroid cancer cells [40]. Here, PIAS3 is linked to thyroid gland papillary carcinoma.