Previous data sustained the role of proteasome inhibitors (i.e., Bortezomib) in disrupting the ER stress response in Myeloma cells by suppressing the endoribonuclease function of IRE1α, through an unknown mechanism possibly involving unknown protein(s) that may act by stabilizing IRE1α-GRP78/Bip association58. Here, HSPA5 is linked to plasma cell myeloma.