BUB1 and Miyoshi myopathy: Next, cluster of differentiation (CD)138-positive plasma cells were isolated, as previously described [27], and BUB1 mRNA in CD138-positive plasma cells from healthy donors (n = 3), patients with MGUS (n = 19), newly diagnosed MM (NDMM) (n = 12), and relapsed/refractory MM (RRMM) (n = 27) was examined to investigate its relationship with disease status.