CCR4 and neoplasm: The number of tumor-infiltrating CD4+ T cells decreased significantly (CCR4−/−: 488 ± 72 CD4+ cells per 1 × 105 tumor cells vs. WT: 1538 ± 355 CD4+ cells per 1 × 105 tumor cells; n = 9, p = 0.0074) with a mean absolute reduction of 1050 ± 343 (72.5%).