ITGA4 and B-cell chronic lymphocytic leukemia: The above-average expression of CD49d in B-CLL cases with a poorer prognosis is also consistent with the demonstration of higher expression levels of this molecule in B-CLL cells from advanced stage patients [53], as well as with the notion that engagement of α4β1, as expressed by B-CLL cells, triggers a signalling cascade eventually preventing apoptosis [54-56].