SPHK1 and viral hepatitis: On the other hand, in viral hepatitis-related HCCs from our other cohort with HBV or HCV infection, there was no evident correlation between the DNA methylation levels of the SPHK1, INHBA, LTB and PDE3B genes and poorer tumor differentiation (Supplementary Fig. 3) (Kuramoto et al. 2017), indicating that participation of these genes in tumor differentiation may occur in a NASH-related HCC-specific manner.