CCL21 and hepatocellular carcinoma: Our previous study has proved that CC-chemokine receptor like 1 (CCRL1) impairs chemotactic events associated with CCR7 in the progression and metastasis of HCC.24 In order to explore the function of another CC-chemokine CCL21/CCR7 axis in HCC, we investigated the complex microenvironment of HCC by TMA, spatial transcriptomic sequencing and single-cell sequencing (Fig. 1a).