VCAM1 and leukemia: Consequently, vascular cell adhesion molecule 1 (VCAM-1), derived from the mesenchymal stem cell membrane (173.8 ± 46.4 nm in thickness) on nanofibrils (1.0 ± 0.2 μm in diameter and 22.0 ± 10.1 μm in length), bound to integrin α4 (VLA-4) on the surface of leukemia stem cells.