HSP90B2P and rheumatoid arthritis: The increased presence of hsp in the RA synovium has been interpreted as a potential door for them to become autoantigens, that is, hsp90 as a ligand to TLR2 [65] or hsp22 binding to TLR4 [66], but what is the real situation inducing the upregulated expression of these hsp in the synovium in the first place?