ITGA4 and acute lymphoblastic leukemia: Also in support, our data show that ALL cells strongly adhere to CP fibroblasts, which is promoted by the upregulation of the expression of ITGA4 (VLA‐4) and ITGAL (LFA‐1) integrins in leukaemic cells and their corresponding ligands, VCAM1 and ICAM1, in CP fibroblasts.