CXCR4 and acute lymphoblastic leukemia: We notably found that cell-surface expression of CXCR4 in T-ALL depends upon the activation of calcineurin (PPP3, named Cn thereafter) [6], a calcium-dependent phosphatase that we previously showed to be critical to T-ALL cell survival, proliferation, migratory activity and leukemia initiating potential using both pharmacological and genetic approaches[7, 8].