Fernández-Sevilla et al. (2020), studying the α4β1/VCAM-1 dependent interaction of ALL cells and fibroblasts within the stroma underlying the CP, found that the ALL cells gained resistance to chemotherapeutical drugs on account of the interaction whereas the fibroblasts gained cancer-associated fibroblast (CAF) markers and secreted proinflammatory markers IL-2, IL-8 and CCL2 [139]. This evidence concerns the gene CCL2 and acute lymphoblastic leukemia.