XCL1, a C class chemokine and also known as lymphotactin, is expressed in various immune cells mainly including CD8 T cells and NK cells.8 The chemotactic property of XCL1 is primarily for recruiting CD8 T cells to the tumor microenvironment to enhance the anti-tumor immune response.9 The detailed mechanism of recruitment is that XCL1 can interact with XCR1 predominantly expressed on dendritic cells (DCs),10–12 which is crucial for inducing tumor-specific CD8+ T cells. The gene discussed is CD8A; the disease is neoplasm.