SOCS1 and myeloid sarcoma: In fact, a previous study demonstrated that downregulation of let-7i in lipopolysaccharide-stimulated dendritic cells (DC) promoted an expansion of Treg cells via upregulation of suppressor of cytokine signalling 1 (SOCS1)43, indicating that the decrease of Treg cell frequency in patients with MS may be partly explained by the effects of exosomal let-7i on DCs.