SPHK1 and hepatocellular carcinoma: In the study of comparing the SE landscape between normal liver and hepatocellular carcinoma cells, it was shown that the SE landscape of cis-acting was extensively reprogrammed in the process of hepatocarcinogenesis, in which HCC cells obtained SEs at the oncogenes including sphingosine kinase 1 (SPHK1) to drive their vigorous expression (Tsang et al, 2019).