CERS1 and liver cancer: Notably, sorafenib treatment led to the downregulation of <i>SMOX</i> (a key catabolic enzyme for spermine), as well as <i>SPHK1</i> and <i>CERS1</i> (critical enzymes involved in sphingosine metabolism), whose high expression levels are associated with poorer survival outcomes in liver cancer patients according to TCGA data.