PROS1 and Miyoshi myopathy: The adhesion of MM plasma cells to BMSCs can stimulate the secretion of factors such as B-cell activating factor (BAFF) from BMSCs that in turn upregulates the expression of anti-apoptotic proteins like myeloid cell leukemia-1 (MCL-1) and B-cell lymphoma-2 (BCL-2), and cell cycle regulating proteins like serine/threonine kinase Pim-2 in MM plasma cells that may lead to chemoresistance (39).