CCL21 and hepatocellular carcinoma: Two TS-SLC genes, SLC29A1 (ENT1) and SLC8A1 (NCX1), are downregulated in tumor cells (TCS) via the EMT-induced zinc finger E box binding homology box 2 (ZEB2)/transforming growth factor (TGF)-BR/nuclear factor (NF)-kB pathway, or miR-223 in HCC, respectively [29].