To determine the expression level of DEK protein in MM cells, we analyzed the FFPE BM samples of MM patients (n = 56) (including the FFPE samples of the 12 out of 41 fresh or frozen samples used in RT-qPCR analysis and 30 BM samples used in FFPE-RT-qPCR analysis) by using either a single or a double IHC staining with antibodies against DEK and CD138. The gene discussed is SDC1; the disease is Miyoshi myopathy.