An example of a dynamic in vitro model in which CLL cells experience shear forces equivalent to those in capillary beds and are made to flow through capillary-like hollow fibers lined with EC has been published by Walsby et al.68 Thanks to this system, the authors could provide evidence for a novel, dynamic, and tractable in vitro model of lymphocyte migration, and confirm that CD49d is a critical regulator of this process in CLL. The gene discussed is ITGA4; the disease is B-cell chronic lymphocytic leukemia.