To determine whether SRD5A1 functions as an oncogene in MM, we functionally knocked down SRD5A1 in myeloma cells by expressing the lentivirus-mediated SRD5A1-shRNA which was under the control of a doxycycline (Dox)-inducible gene promoter thus avoiding the adverse effect of long-term knockdown. The gene discussed is SRD5A1; the disease is Miyoshi myopathy.