These results were consistent with a more recent report that very late antigen-4 (VLA-4), which is composed of a CD49d and CD29 dimer, is an important integrin for retention of CLL cells in the microenvironment by interacting with its ligand vascular cell adhesion molecule 1 (VCAM-1 or CD106) on stromal cells (75). This evidence concerns the gene ITGA4 and B-cell chronic lymphocytic leukemia.