XBP1 and myeloid sarcoma: Analyses of brains from human MS patients have consistently shown augmented levels of ER stress markers such as BiP, XBP1 and CHOP in demyelinating lesions compared to healthy white matter or non-MS brain, establishing the relevance of this pathway in the death of myelin-producing oligodendrocytes and inflammatory responses of immune-cells within sites of degeneration [22].