CCR7 and acute lymphoblastic leukemia: Interestingly, both CCR7 and CXCR4 are upregulated by zeta-chain-associated protein kinase 70 (ZAP70) via the activation of ERK signaling, and high expression of ZAP70-CCR7 confers an increased risk for CNS involvement in T-ALL patients [119] (Figure 2C).