Enforced expression of miR-155 in CD14+ blood monocytes from RA and healthy subjects stimulated the production of TNF-α (supplementary Fig. S4, available at Rheumatology Online) consistent with previous observations [6, 11], but in addition, stimulated the production of the chemokines CCL3, CCL4, CCL5 and CCL8 in RA and CCL3 in healthy monocytes compared with controls transfected with CM (Fig. 3). The gene discussed is CCL4; the disease is rheumatoid arthritis.