XBP1 and plasma cell myeloma: AZD2461 (an effective PARP inhibitor)/UCN-01 combined inhibit PARP (poly (ADP ribose) polymer) and CHK1, reducing the expression of xbp1 (X-Box Binding Protein 1) in cells by downregulating c-Myc (cellular-myelocytomatosis viral oncogene) and upregulating the pro-apoptotic molecule CHOP (C/EBP-homologous protein), leading to UPR (unfolded protein response) imbalance and cell death and trigger autophagy through PERK/eIF2alpha in MM (multiple myeloma) and IRE1alpha/JNK1/2 in PEL (primary effusion lymphoma) cells [83].