XCL1 and hepatocellular carcinoma: In the previous studies, the vaccine had been developed to increase the expression of XCL1+ CD8+ T cells or XCR1+ DCs, separately, leading to induce potent anti-tumor immunity and kill the tumor cells in few tumors, especially in HCC and lung cancer.28,29 In addition, the overexpression of XCR1 was correlated to better outcomes in HCC patients with the treatment of sorafenib.13 Co-activation of XCL1 and XCR1 probably enhances the high anti-tumor efficacy and improves the prognosis of HCC.