BCL2 and B-cell chronic lymphocytic leukemia: Researchers have demonstrated B-cell receptor (BCR) signaling as a central driver for CLL, in addition to other contributors such as aberrant anti-apoptotic (e.g., BCL-2, TRAIL, MCL-1), pro-survival (e.g., IL-4R and IL-21R), and cell-trafficking (e.g., CCR7 and CXCR4) proteins.