Abnormal activity of a number of transcription factors has been implicated in multiple myeloma development, including NF-κB, MAF, MYC, and interferon regulatory factor 4 (IRF4) (Dean et al., 1983; Keats et al., 2007; Palumbo et al., 1989; Shaffer et al., 2008). The gene discussed is IRF4; the disease is AL amyloidosis.