In this regard, the activation of IRE1/XBP1 pathway is involved in the progression of different tumors including glioblastoma, triple-negative breast cancer and multiple myeloma [60] and may contribute to metastatic progression and chemoresistance [61] Interestingly, depletion or knockdown of p53 has been shown to increase IRE1α/XBPI pathway and BiP expression, in the presence or absence of ER stress, as p53 drives IRE1α protein to degradation through proteasome, while ATF6 and PERK/eIF2a pathways are suppressed [62]. This evidence concerns the gene ERN1 and plasma cell myeloma.