Using idelalisib to interfere with VLA-4-VCAM-1 interaction, we found a strong inhibition of CLL adhesion to TNFα-treated endothelium in VLA-4 high expression group (40.6% inhibition of adhesion) compared with VLA-4 low expression group (12.1% of inhibition of adhesion) (Figure 3C, n=10, p<0.05). Here, VCAM1 is linked to B-cell chronic lymphocytic leukemia.