IL21R and neoplasm: As an illustration, high levels of BRD4 co-localize in CLL cells with super-enhancer sites of genes and microRNAs belonging to the BCR-mediated signaling pathway with possible tumor-initiating activity, including miR-21, miR-15, TCL1, IL21R, and IL4R. Accordingly, in a mouse model of CLL, exposure to the BET inhibitor PLX51107 promoted an expression downmodulation of several tumor-associated genes, followed by consistent reduction in tumor burden (Ozer et al., 2018).