SQLE and hepatocellular carcinoma: Terpenoid backbone biosynthesis and steroid biosynthesis are essential routes for producing multiple steroids such as cholesterol, steroid hormones, vitamin D2, vitamin D3, etc. Apart from their crucial roles in breast and prostate cancer [34, 35], the key enzymes such as Pmvk, Fdps, Sqle involved in the two pathways are frequently up-regulated in multiple cancer types including HCC depending on the TCGA and GTEx database (http://gepia.cancer-pku.cn).