Our demonstration that inhibition of SYK or BTK blocks the TEM of CLL cells toward chemokine is in agreement with these previous studies and supports the notion that the mobilizing effects of fostamatinib and ibrutinib result partly from enhanced exit from lymph nodes due to release of α4β1-dependent adhesive interactions and partly from reduced lymph node entry due to blockade of CCL21-directed TEM across the high endothelial venules. This evidence concerns the gene BTK and B-cell chronic lymphocytic leukemia.