COX-2/PGE2 can also inhibit the secretion of CCL5 and XCL1 by natural killer (NK) cells and the expression of CCR5 and XCR1 in conventional type 1 dendritic cells (cDC1), which can impair the function of NK cells and the accumulation of cDC1 in the TME, which are responsible for tumor immunity (24). The gene discussed is XCL1; the disease is neoplasm.