The transcription factors Ikaros (IKZF1) and Aiolos (IKZF3) that belong to the Ikaros zinc finger family (IKZF), were first identified as lenalidomide-dependent CRL4CRBN substrates in multiple myeloma cell lines (Kronke et al., 2014; Lu et al., 2014). The gene discussed is IKZF1; the disease is plasma cell myeloma.