Although IRF4 functions as a tumor suppressor gene in early B-cell development (Acquaviva et al., 2008), in multiple myeloma IRF4 is a well-established oncogene (Shaffer et al., 2008),with oncogenic implications extending to adult leukemias (De Silva et al., 2012) and lymphomas (Bisig et al., 2012), as well as pediatric leukemia. The gene discussed is IRF4; the disease is leukemia.