The novel findings in this study are the characterization of idelalisib effects on CLL cell adhesion to BMSC and EC under static and shear flow conditions, its effects on CLL cell viability in side-by-side co-cultures with BMSC and EC, and the role of the VLA-4-VCAM-1 axis in AKT pathway activation in CLL. This evidence concerns the gene AKT1 and B-cell chronic lymphocytic leukemia.