CXCR4 and B-cell chronic lymphocytic leukemia: Interestingly, PKD involvement in BCR-mediated CXCR4/CXCR5 downregulation observed in our CLL samples appears to be different from the CXCL12/CXCR4 signaling pathway, which leads to CXCR4, but not CXCR5 and CD62L downregulation in the mouse model of TCL-1 CLL-like disease [50].