MYOM2 and plasma cell myeloma: Detection of M-protein, a monoclonal immunoglobulin produced by malignant plasma cells in the bone marrow, is crucial in multiple myeloma (MM) diagnostics, treatment, and follow-up.1 M-protein is most commonly detected and quantified with serum protein electrophoresis (SPEP) using patient serum or urine as the starting material for analysis.