Conversely, the IgL enhancer, which is one of the largest enhancers in B cells, plasma cells, and myeloma, appears to be active regardless of whether or not a productive IgL is expressed, as indicated by chromatin accessibility and IKZF1-occupancy in IgK- and IgL-expressing myeloma cell lines (Supplementary Fig. 9d, bottom). This evidence concerns the gene IKZF1 and plasma cell myeloma.