CCL20 and hepatocellular carcinoma: In severely hypoxic tumor regions of HCC, regulatory T cells (Tregs) and cDC2 can be attracted by CCL20 and CXCL5, and hepatoma cell-derived extracellular adenosine can recruit pDCs via the hypoxia-inducible factor (HIF)-1α/CD39/CD73 signaling pathway [15, 16].