To evaluate the impact of Syk inhibition by TAK-659 on the ex vivo chemotaxis of CLL cells, we analyzed the ability of CLL cells to migrate toward CXCL12, CXCL13 and the BMSC cell line HS-5 by performing transmigration assays using bare polycarbonate membranes. Here, SYK is linked to B-cell chronic lymphocytic leukemia.