CXCL12 and acute lymphoblastic leukemia: Although no reports have linked high CXCR4 expression with a poor prognosis in T-cell ALL, it has been shown that T cell ALL interaction with CXCL12 is required for maintenance of disease in mouse models and that T ALL cells from both humans and mice show higher CXCR4 expression when compared to healthy cells (42, 43).