CCR4 and adult T-cell leukemia/lymphoma: Importantly, the gain‐of‐function CCR4 phenotype in ATLL cells gave the cells a competitive advantage over cells expressing wild‐type CCR4, leading to increased growth and survival.40 The parallels between CCR4‐Q330 and CCR4‐Δ40 could perhaps be predicted given the close proximity of the 2 truncations at positions 320 (CCR4Δ40) and 330 (CCR4‐Q330).