PDCD4 and B-cell chronic lymphocytic leukemia: Interestingly, while PDCD4 was found to be a common target of CXCL12 signaling in all CLL samples examined, phospho-HSP27 and total HSP27 protein were only detectable by western blot in a subset of ∼25% (3 out of 12) of CLL patients examined (representative western blot Figure 6B).