Intriguingly, a case report of a pediatric T-ALL expressing CCR9 (and CD103 or αEβ7 integrin) at diagnosis, that switched to acute myeloid leukemia at relapse with disease localization to the gut has been reported (110), suggesting a role for CCR9 in the gut tropism of these leukemic cells. Here, CCR9 is linked to acute myeloid leukemia.