CCR9 is as an interesting target for the treatment of human CCR9<sup>+</sup>-T cell acute lymphoblastic leukemia, since its expression is limited to immature cells in the thymus, infiltrating leukocytes in the small intestine and a small fraction of mature circulating T lymphocytes.
We have previously demonstrated that the CCR9/CCL25 signaling pathway plays an important role in drug resistance in human acute T-lymphocytic leukemia (T-ALL) by inducing activation of ERM protein with polarized distribution in T-ALL cell line MOLT4.
Finally, through RNA interference we demonstrated that the oncogenic isoform in T-ALL, Notch1, plays a role in controlling CCR5 and CCR9 expression and functions.