TNFRSF17 and plasma cell myeloma: al. study, primary bone marrow samples were taken from eighth patients with MM to analyze the expression of BCMA on the surface of MM cells and myeloma progenitor cells (MPC), MPCs do not have the plasma cell phenotype and are not completely differentiated [5], they have a weaker response in patients to treatments such as stem cell transplantation and proteasome inhibiting [67].