HSP90B1 and myositis disease: Except for sporadic inclusion-body myositis, where the ER chaperones calnexin, calreticulin, Grp78, Grp94 and ERp72 are upregulated and colocalize with intracellular aggregates [11,12], the present knowledge about changes in ER chaperone level and distribution among myofibers of myositis patients is far from complete.