CXCL12 and B-cell chronic lymphocytic leukemia: CXCR4 is highly expressed on the surface of peripheral blood circulating CLL cells, and is important for CLL cell survival, migration, and interaction with the protective microenvironment.10, 12, 56, 57 CXCL12 ligands produced by stromal cells induce CLL cell chemotaxis and migration through activation of CXCR4.11, 12, 13 In this study, we found that CUDC‐907 not only reduced CXCL12‐induced smCXCR4 expression but also inhibited CXCR4 phosphorylation at Ser339.