CXCL12 and acute lymphoblastic leukemia: Ibrutinib, an inhibitor of Bruton's tyrosine kinase (BTK), is used to treat Waldenström's macroglobulinaemia, mantle cell lymphoma and lymphoblastic leukaemia, which also inhibits SDF‐1 induced AKT and MAPK activation, leading to the inhibition of the migration and proliferation of leukaemia cells.80