Given the known role of the CEBP family of transcription factors in carcinogenesis (Sebastian and Johnson, 2006), the strong overexpression of CEBPB, as well as CEBPA and CEBPD, may contribute to the strong proliferative drive of Eμ-XBP-1s B transgenic cells that, through the acquisition of additional genetic/epigenetic lesions, could promote the development of MGUS and MM. The gene discussed is CEBPD; the disease is Miyoshi myopathy.