Hairy cell leukemia cells are characterized by high expression of receptors for molecules such as C-X-C chemokine receptor type 4 (CXCR4), very late antigen-4 (VLA-4), adhesion molecules including integrins and CD44, B cell antigen receptor (BCR), and CD40 antigen (6, 22, 23). Here, CXCR4 is linked to hairy cell leukemia.