We speculate that HSP70 in medium may bind its specific surface receptor on the RA FLSs, and activate intracellular anti-inflammatory signal transduction pathways such as JAK2-STAT3-SOCS3, which can inhibit the TNF-α induced degradation of IκB as well as subsequent activation and nuclear translocation of NF-κB. Here, SOCS3 is linked to rheumatoid arthritis.