According to our results, Bor increased GRP78/BiP levels in all MM cell lines investigated, consistent with ER stress induction and UPR activation [30]; however, the concurrent reduction of CHOP observed in the three human cell lines and the unchanged CHOP levels observed in the murine cell line indicate that such Bor-induced UPR activation has a pro-survival effect and likely participates to lower MM cells sensitivity to Bor cytotoxicity [51]. The gene discussed is HSPA5; the disease is Miyoshi myopathy.