The loss of E-cadherin expression and the subsequent induction of N-cadherin are known as hallmarks of the epithelial-to-mesenchymal transition, an essential initial step in the process of metastasis in solid tumors.1 Although multiple myeloma (MM) cells are non-epithelial cells, Roccaroet al. and Azabet al. 2,3 suggested that reduced E-cadherin expression in MM cells can promote extramedullary disease (EMD)in vitro and in an animal model, partly due to epithelial-to-mesenchymal-transition-like features. The gene discussed is CDH1; the disease is Miyoshi myopathy.