VCAM1 and leukemia: Given the increased expression of ITGA4 (VLA‐4) and its ligand VCAM‐1 after leukaemia/CP fibroblast co‐culture (Figure 3) and the relevance of the interactions between VLA‐4 on leukaemic cells and VCAM‐1 on bone marrow stromal cells in promoting adhesion and chemoresistance [20], we used anti‐VLA‐4 antibodies to study the effects of the blockade of VLA‐4/VCAM‐1 interaction on CP fibroblast‐induced chemoprotection.