In addition to blocking BCR signaling, inhibition of PI3Kδ is believed to interrupt CXCR4 and CXCR5 signaling and subsequent CLL cell homing, causing redistribution of these cells into circulation, removal from the lymph node microenvironment’s pro-survival signals and sensitization to apoptosis.20,23,24. Here, BCR is linked to B-cell chronic lymphocytic leukemia.