IRF4 is emerging as an oncogene involved in a subset of hematological malignancies, including multiple myeloma (MM [22]), the activated B cell-like subtype of diffuse large B cell lymphoma (ABC-DLBCL [23, 24]), anaplastic large cell lymphoma (25, 26), and human T cell leukemia virus type 1 (HTLV-1)-associated adult T cell leukemia/lymphoma (ATLL [27, 28]). This evidence concerns the gene IRF4 and plasma cell myeloma.