CCR6 and neoplasm: Since healthy virus-naive individuals’ CMV-specific CD8+ T cells lack expression of CCR6, CXCR3, and CCR4, enhanced expression of CCR6 and CXCR3 via IL-2/IL-15/IL-21 conditioning might be a feasible approach to enhance CMV-specific CD8+ T cell trafficking to infection sites and eliciting anti-tumor secretions such as IFNγ and TNF-α (130).