CCR4 is also widely expressed on surface of tumor cells of most patients with adult T-cell leukemia/lymphoma (ATL) and is selectively expressed in approximately 40% of patients with other subtypes of peripheral T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL) [5–10]. The gene discussed is CCR4; the disease is peripheral T-cell lymphoma, not otherwise specified.