Tumor-resident CD8+ T cells, polarized by such a type 1 cytokine–rich environment, downregulate tumor-specific immune responses by facilitating the local migration of CD4+Foxp3+ Tregs through the accumulation of several CCR5-specific cytokines, such as MIP-1α (CCL3) and MIP-1β (CCL4). The gene discussed is CCR5; the disease is neoplasm.