The effects of truncation on ligand‐induced endocytosis also closely mirror the effects of CCR4‐truncating mutations observed in a study of ATLL in which ligand‐induced CCR4 internalization in ATLL cell lines was impaired by C‐terminal truncation at glutamine 330 (CCR4‐Q330), with a concomitantly enhanced chemotactic response toward CCL17 and CCL22. This evidence concerns the gene CCL22 and adult T-cell leukemia/lymphoma.