Fig 1: SphK2 deficiency downregulates CERT both in vivo and in vitro.A, B Wild-type (WT) and Sphk2 knockout (KO) mice were fed with a high-fat, high-sugar diet (HFHSD) for 46 weeks. A Proteins were extracted from non-tumorous liver tissues and analyzed using Western blotting. Expression levels of the indicated proteins were quantified; n = 8. B mRNA expression of Cert1, the gene encoding mouse CERT, was examined by real-time RT-PCR; n = 8. C–E Huh7 hepatic cells were transduced with lentiviral-based short hairpin RNA (shRNA) to knock down SphK2 and then treated with a combination of free fatty acids (FFA, 200 µM palmitate + 400 µM oleate) for 48 h. C, E Proteins were extracted from cells and analyzed using Western blotting. The CERT protein expression and phospho-p65 over total p65 (p-p65/t-p65) were quantified; n = 5. D mRNA expression of CERT1, the gene encoding human CERT, was examined in the presence and absence of the FFA treatment by real-time RT-PCR; n = 4. A–E Data are expressed as mean ± SD. *p < 0.05; **p < 0.01; ***p < 0.001; versus control. F The correlation of SPHK2 and CERT1 mRNA expression was analyzed in human HCC subjects with body mass index > 25. Data are sourced from TCGA (https://portal.gdc.cancer.gov).