BTK and B-cell chronic lymphocytic leukemia: BTK inhibition by ibrutinib suppressed CXC-chemokine ligand 12 (CXCL12), CXCL13, and CC-chemokine ligand 19 (CCL19)-induced signaling, adhesion, and the migration of primary chronic lymphocytic leukemia (CLL) cells [17], and also led to reduced surface membrane levels of CXC-chemokine receptor 4 (CXCR4) and impaired CXCR4 function [18].