IRF4 and neoplasm: Many anti-tumor effects of these drugs are related to an increase in degradation of transcription factors Aiolos and Ikaros (encoded by IKZF-3 and IKZF-1 respectively); this in turn can lead to down-regulation of c-Myc and interferon regulatory factor 4 (IRF4) in MM cells, and also to immunomodulation and effector T cell co-stimulation [17, 21].